The Scottish Health Survey 2022 – volume 2: technical report

Chapter 1 Methodology and response

Victoria Wilson & Stephen Hinchliffe

1.1. Introduction

1.1.1 The Scottish Health Survey series

The Scottish Health Survey (SHeS) series was established in 1995 to provide data about the health of the population living in private households in Scotland. It was repeated in 1998 and 2003 and has been carried out annually since 2008.

The 2018-2023 surveys are being conducted by The Scottish Centre for Social Research in collaboration with the Office for National statistics (ONS), the Social and Public Health Sciences Unit (MRC/CSO SPHSU) at the University of Glasgow, the Centre for Population Health Sciences at the University of Edinburgh and the Public Health Nutrition Research Group at the University of Aberdeen^[1].

Fieldwork for the 2020 and 2021 surveys was significantly affected by the COVID-19 pandemic, while the 2022 survey was a transitional year from pandemic approaches to a more standard SHeS methodology. Fieldwork for SHeS 2020 was suspended in March 2020. Data for some of the key measures from SHeS was collected via a telephone survey in August and September 2020. Due to the testing of a new methodology for the SHeS survey within the context of the COVID-19 pandemic, the survey results for 2020 were presented as experimental statistics. These results have not been included in time series analysis presented in Volume 1 of this report.

Further details of the approaches used for the 2021 survey can be found in Chapter 1 of the Scottish Health Survey 2021 - volume 2: technical report. Please note that while the 2021 survey includes most of the questions and key indicators from the face-to-face surveys, the change in mode of administration, along with the different approach to sampling, is likely to have impacted the responses received and thus comparability with the previous SHeS data.

1.1.2 The SHeS 2022 Fieldwork

There were two phases of fieldwork for SHeS 2022 for both the Core sample and Child Boost samples.

During Phase 1 for the Core sample, potential participants were contacted by letter and recruited to participate by interviewers knocking on their door, in what is termed a 'knock-to-nudge' methodology. Interviews were conducted by telephone. This phase covered the months of March and April 2022 and included similar content to earlier survey years, as well as interviews with or on behalf of children.

The Core sample Phase 2 began in May 2022. Potential respondents were again contacted by letter but were then invited to take part in an in-home interview. A telephone contingency was retained for respondents unwilling to have the interviewer enter their home due to health concerns. This second phase only began once COVID-19 restrictions in Scotland had been lifted to the extent that Scottish Government ministers and the Chief Medical Officer gave permission for in-home interviewing to recommence on Scottish Government surveys. The shift to an in-home approach had a positive impact on sample composition, with greater representation in the final sample of respondents in the most deprived Scottish Index of Multiple Deprivation (SIMD) quintiles compared to a solely telephone or knock-to-nudge approach.

Whilst there was a shift from telephone to in-home data collection between phases 1 and 2, because both phases utilised doorstep/in-person contact it was assumed that the response rate would not change significantly – unlike if there was a shift from fully remote 'opt-in' recruitment. As such, a single sample was drawn to cover both of the Core phases.

Between March and July 2022, participants from the child boost sample continued to be invited to opt in via letter. Fieldwork for the child boost sample was suspended in August 2022 to allow the transition to the second phase which utilised a sample linked to the Community Health Index (CHI) database. This was undertaken following approval from the Scottish Government's Public Benefits and Privacy Panel. The transition to the use of the CHI database was undertaken to increase the efficiency of the sample. Prior to the suspension of fieldwork at the outset of the COVID-19 pandemic, the child boost sample was drawn without any indication as to whether there may be children under 16 living in the sampled households. This meant that approximately four-fifths of households visited did not have children under the age of 16 living in them. The transition to sampling via CHI database linkage was used to try and identify households with children under 16 living in them and while a margin for error remains with this approach, it was found to be much more efficient than the previous sampling approach.

1.1.3 Aims of the Scottish Health Survey

The purpose of SHeS is to provide information at national level about the health of the population and the ways in which lifestyle factors are associated with health. This level of information is not available from administrative or operational databases, as hospitals and GPs are not able to collect detailed information about peoples' lifestyles and health- related behaviours. In addition, it is crucial that the Scottish Government has information about the health of the population, including people who do not access health services regularly.

The specific aims of SHeS are:

• To estimate the prevalence of particular health conditions in Scotland.
• To estimate the prevalence of certain risk factors associated with these health conditions and to document the pattern of related health behaviours.
• To look at differences between regions and between subgroups of the population in the extent of their having these particular health conditions or risk factors, and to make comparisons with other national statistics for Scotland and England.
• To monitor trends in the population's health and health related behaviour over time.
• To make a major contribution to monitoring progress towards health targets.

Each survey in the SHeS series has a set of core questions and measurements (height and weight and, if applicable, blood pressure, waist circumference and saliva samples), plus modules of questions on specific health conditions and health risk factors that vary from year to year. Each year the main sample has been augmented by an additional boosted sample for children.

The purpose of the SHeS 2022 survey was to provide this same information at national level in the context of the transition from the height of the COVID-19 pandemic. The SHeS series now has trend data going back 27 years and providing this time series is an important function of the survey.

1.1.4 The 2022 survey

The 2022 Scottish Health Survey was designed to provide data at national level about the population living in private households in Scotland. The survey covered all ages.

The target sample size for the 2022 survey was the same as that for 2018, 2019 and 2021. Due to the reintroduction of doorstep contact in late 2021 and the reintroduction of in-home interviewing in May 2022, the issued sample was smaller than in 2021.

An initial sample of 8,689 Core addresses (main sample version A and main sample version B) and 16,266 child boost addresses were drawn from the Postcode Address File (PAF) in 2022 on the basis of the Core sample being conducted as telephone/in-home with doorstep contact and the child boost sample being conducted via opt-in. This sample was split into 11 monthly waves of fieldwork from March to January.

For the child boost sample, only the first five months were issued, as the sample was superseded by a smaller CHI linked sample which was worked over five months between September 2022 and January 2023 (August 2022 was a transition month to the new sample with no child boost sample issued or worked for this month). A replacement child boost CHI linked sample (1,151 addresses) was drawn for the last five months of 2022.

The Core (versions A and B) sample of 8,869 addresses were grouped into 347 interviewer assignments, with around 32 assignments being issued to interviewers each month between March 2022 and January 2023.

For Phase 1 of the child boost, participants were asked to opt-in using an online portal, or by contacting the NatCen freephone team. They were asked to leave a telephone number on which an interviewer would call them back. Addresses were only assigned to interviewers after the household had opted into the survey. Assignments comprised up to 10 addresses and a mix of all sample types.

For Phase 2 of the child boost, participants were visited on the doorstep and up to 2 children per household were invited to take part in an in-home interview. The sample of 1,151 CHI linked addresses were grouped into 77 interviewer assignments, with around 14 assignments being issued to interviewers each month between September 2022 and January 2023.

ScotCen enlisted the Office for National Statistics (ONS) to assist with the interviewing for the duration of the 2018-2023 contract. ONS interviewers were only used for the Core Version A sample element of the 2022 survey. As a result, ONS were allocated approximately 304 of the sampled Core addresses.

Fieldwork for the 2022 survey was paused between the announcement of the Queen's passing until after her funeral, with fieldwork extended until March 2023 as a result to allow for the initial fieldwork periods and interview mop ups to be worked.

The table below shows the total number of addresses (mainstage and additional) issued for each sample type and the people eligible for interview within each sample type.

Table 1: Number of addresses and people eligible for interview, 2022

Sample type	Number of addresses issued in 2022	Eligible for interview
Core version A	5,769	Max of 10 adults (age 16+) and 2 children (age 0-15)
Core version B	2,920	Max of 10 adults (age 16+) and 2 children (age 0-15)
Child boost	16,266 opt-in 1,511 CHI-linked	Only households containing children aged 0-15 were eligible to participate (up to two children at these households were eligible to be interviewed)
Total	26,466

Data collection involved a main computer assisted personal (CAPI) or telephone interview (CATI), and online or paper self-completion questionnaire.

Standardised interviewer-administered height and weight measurements were reintroduced as part of in-home interviews in 2022. For interviews conducted by telephone, no height and weight measurements or biological measures could be taken. Participants were asked to estimate their own height and weight during these interviews and for any face-to-face interviews where accreditations for standardised measurements had not yet taken place.

In previous years, the Core version B sample completed a biological module, and these addresses were only assigned to trained bio interviewers. For 2021, as all interviews were conducted by telephone no biological measurements were taken, however, these were reintroduced gradually during 2022 as the panel of accredited interviewers was built back up. Version B interviews included a slightly longer self-completion to cover the depression, anxiety, self-harm and attempted suicide questions which are included in the biological module.

1.1.5 The 2022 SHeS annual report

The 2022 report consists of two volumes, published as a set under 'The Scottish Health Survey 2022'. Volume 1 presents results for adults and children on a variety of health topics. This report (Volume 2) provides methodological information and survey documentation. Both volumes are available on the Scottish Government's website along with a short summary report of the key findings from the 2022 survey (Scottish Health Survey). Supplementary web tables are also available on this website. These provide a large number of breakdowns by age group, deprivation, income and limiting long-term condition. An interactive data dashboard is also available presenting key indicators for Scotland, NHS Boards and local authority areas.

1.1.6 Comparisons with previous surveys in the SHeS series

In the 2022 report, comparisons are made with data collected earlier in the series (1998-2019 and 2021 for children and 2003-2019 and 2021 for adults). However, it should be noted that, due to the difference in method for 2021, caution should be applied when comparing results from this survey year to 2021. For more information, see Chapter 2 of the Scottish Health Survey 2021: volume 2 technical report.

In addition, this report includes analysis from some combined datasets: one for the years 2018, 2019, 2021, 2022 combined and one for the years 2021 and 2022 combined to aid analysis of small subsamples of the population and/or for questions which are included in the survey every second year. Combining data across years in this way allows for a more detailed analysis of subgroups in the sample and allows for analysis of questions with small sample sizes in one survey year.

1.1.7 Health Board and local authority level analysis

Since 2008, the SHeS sample has been designed to be representative of adults at Health Board level (for all Health Boards) following four years of data collection and in 2018 the sample size was increased to allow analysis by local authority. Analysis of the 2018, 2019, 2021 and 2022 data combined by NHS Health Board and by local authority is published via the online SHeS data dashboard on the Scottish Government website. Areas with larger samples may be able to analyse data at their area level based on fewer years of data collection and users should consult the SHeS website for further guidance on sub-geographies analysis.

Changes in the sample design for the 2012 survey mean that users are not advised to combine data for periods spanning 2011 and 2012. Since 2012, however, the sample has been designed to be representative of the population of Scotland at Health Board level for every four-year period. Hence the survey can be analysed using combined data from 2012 to 2015, 2013 to 2016, 2014 to 2017, 2015 to 2018, 2016 to 2019, 2017/2018/2019/2021 or 2018/2019/2021/2022. It should be noted that no data for 2020 is available by Health Board.

1.1.8 Access to SHeS data

Data from the 2022 survey will be deposited at the UK Data Service along with a combined 2018/2019/2021/2022 dataset and a combined 2021/2022 dataset. Datasets from earlier years in the series are also deposited here (www.ukdataservice.ac.uk).

1.2 Sample design

1.2.1 Requirements

The sample specification for the 2022 SHeS was designed by the Scottish Government. The design was coordinated with the designs for the Scottish Household Survey (SHS) and the Scottish Crime and Justice Survey (SCJS) to improve survey efficiency and to allow the samples of the three surveys to be pooled for further analysis^[2].

There were two elements to the SHeS sample in 2022:

1) Main adult sample - to allow annual reporting of Scotland level results and results at Health Board and local authority level using the 2018, 2019, 2021 and 2022 data combined. This required an annual interview target of 5,112 adults for Scotland as a whole and a minimum target of 125 for each local authority. There was an additional requirement for a minimum of 1,000 adults to complete each biological measure each year.

2) Child sample boost – overall there was a requirement for 2,031 child interviews for Scotland. As the main sample was only expected to yield 1,026 child interviews, a further 1,005 interviews were required from a separate boost sample.

1.2.2 Sample design and assumptions

In 2022, the knock-to-nudge and in-home samples both utilised a two-stage clustered sample design, with intermediate geographies randomly selected at the first stage and address points at the second stage, was used. With the exception of Orkney, Shetland and Na h-Eileanan Siar councils, the sample was clustered by intermediate geographies (IG) with one quarter of IGs selected for each year of fieldwork. In Orkney, Shetland and Na h-Eileanan Siar the sample was clustered by data zone.

1.2.3 Main sample

As stated above, the annual target sample size for Scotland was 5,112 adults with a minimum local authority target sample size of 125 adults. These sample sizes were the minimum required to allow effective reporting of Scotland-level results annually and Health Board and local authority results with four years of data combined. An iterative approach was taken to efficiently allocate the sample across all Health Boards and local authorities. For the first iteration, 4,000 adult interviews were allocated across local authorities in proportion to the adult population. Any local authorities allocated fewer than 125 adult interviews had their allocation increased to 125.

The remaining sample was then allocated over the remaining local authorities. Where allocations were not whole numbers the number was rounded up. This resulted in a total target of 5,112 adult interviews. The results of the allocation are shown in Table 2.

Table 2: SHeS target annual adult interviews, 2022, by Health Board

Health Board	Target Annual Adult Interviews
Ayrshire and Arran	375
Borders	125
Dumfries and Galloway	125
Fife	271
Forth Valley	375
Grampian	488
Greater Glasgow and Clyde	1,075
Highland	297
Lanarkshire	482
Lothian	749
Orkney	125
Shetland	125
Tayside	375
Western Isles	125
Total	5,112

To allow for reporting at local authority level over a four-year period (2018/2019/2021/2022) and coordination with the sample selection of the SHS and SCJS, the required sample sizes were set at local authority level. This was done by allocating the target Health Board samples to local authorities proportionate to population.

The number of addresses selected in order to provide the target number of interviews for the opt-in part of the sample was calculated by:

1) Estimating the number of productive adult interviews per co-operating household. Considering response data from previous years, it was estimated that there would be an average of 1.5 interviews per co-operating households in each local authority.

2) Allocation of the target interviews and associated estimate of co-operating households to local authority strata proportionate to population.

3) The response rate assumptions for local authorities for 2022 were then estimated based on the variation across local authorities in response to the 2017, 2018 and 2019 face-to-face surveys.

4) The final step was to estimate the level of ineligible addresses. As for previous survey years, the estimates were calculated at local authority level and based on the average level of ineligible addresses from previous years of SHeS, SHS and the SCJS.

Table 5 shows the number of selected addresses used for the main sample in 2022 knock-to-nudge and in-home combined.

1.2.4 Child boost sample

For the 2022 survey, 2,031 child interviews were required. It was estimated that the knock-to-nudge and in-home Core sample would provide 1,026 child interviews, therefore, to reach the target number of child interviews, a child boost sample was required to yield a further 1,005 interviews.

For the child boost, up to July 2022 potential respondents were initially contacted by letter and asked to opt-in to an interview conducted over the phone. A child boost opt-in sample was used for this part of the year. From September 2022, interviews were conducted in the home. For this part of the year, the child boost sample was linked to health records via the Community Health Index (CHI) to identify households with children (the child boost in-home sample). This significantly improved the sample efficiency and response levels. This linkage was carried out by the CHI Linkage (CHILi) Indexing Team at Public Health Scotland.

Table 3: Target annual child interviews, 2022, by Health Board

	Expected child interviews from main sample	Child interviews from boost	Total child interviews
Ayrshire and Arran	75	70	149
Borders	25	21	50
Dumfries and Galloway	25	27	50
Fife	54	71	108
Forth Valley	75	60	149
Grampian	97	110	194
Greater Glasgow and Clyde	219	216	427
Highland	60	59	118
Lanarkshire	97	131	191
Lothian	149	163	298
Orkney	25	0	50
Shetland	25	0	50
Tayside	75	77	149
Western Isles	25	0	50
Total	1,026	1,005	2,031

The process for calculating the number of addresses to select for the child boost sample was as follows:

1) The child boost target of 1,005 child interviews was allocated proportionally to local authorities based on the child (under 16) population. If the number expected from the child boost was less than 10, then the local authority boost target was set to zero. The following table shows the child interview targets for the main sample and child boost sample by Health Board.

2) The number of co-operating households with children required in each Health Board for the child boost sample was estimated using the performance of the child boost samples in the surveys between 2013 and 2015.

3) For the child boost opt-in sample, to estimate the proportion of child-less households, data from child boost samples between 2012 and 2015 was used. As there was little variation across different areas, a Scotland level estimate of households without children (80%) was used. This is applicable to the child boost opt-in addresses only.

4) For the child boost in-home addresses, CHI linkage was performed to identify homes where health records indicated that a child was resident. It was assumed the CHI linking would identify 20% of sampled households as having a child resident. An additional assumption of 64% accuracy of the CHI records was included to allow for cases where health records may not be up-to-date or households had moved.

5) The assumptions made on ineligible addresses for the main sample were applied to the address calculations for the child boost sample.

The total numbers of addresses issued for the child boost sample are shown in Table 4.

Table 4: Selected addresses issued by strata in 2022 – Child Boost opt-in sample (March to July 2022) and in-home (September 2022 to January 2023)

Sample strata	Child Boost opt in	Child boost in-home	Total sample
Aberdeen City	492	31	523
Aberdeenshire	634	62	696
Angus	317	16	333
Argyll & Bute	247	14	261
Clackmannanshire	129	6	135
Dumfries & Galloway	368	15	383
Dundee City	460	33	493
East Ayrshire	280	27	307
East Dunbartonshire	317	31	348
East Lothian	336	31	367
East Renfrewshire	297	16	313
Edinburgh, City of	1464	78	1542
Eilean Siar	0	0	0
Falkirk	368	30	398
Fife	1154	80	1234
Glasgow City	2228	154	2382
Highland	865	50	915
Inverclyde	297	23	320
Midlothian	243	21	264
Moray	218	13	231
North Ayrshire	364	19	383
North Lanarkshire	1187	102	1289
Orkney Islands	0	0	0
Perth & Kinross	428	26	454
Renfrewshire	741	57	798
Scottish Borders	264	19	283
Shetland Islands	0	0	0
South Ayrshire	286	15	301
South Lanarkshire	961	72	1033
Stirling	218	12	230
West Dunbartonshire	403	31	434
West Lothian	700	67	767
Total	16,266	1,151	17,417

Table 5: Selected addresses issued by strata in 2022 – K2N & in-home core sample (adults only)

Sample strata	Main adult sample
Aberdeen City	262
Aberdeenshire	288
Angus	204
Argyll & Bute	242
Clackmannanshire	651
Dumfries & Galloway	193
Dundee City	204
East Ayrshire	216
East Dunbartonshire	187
East Lothian	206
East Renfrewshire	213
Edinburgh, City of	198
Eilean Siar	182
Falkirk	465
Fife	876
Glasgow City	324
Highland	232
Inverclyde	189
Midlothian	185
Moray	201
North Ayrshire	207
North Lanarkshire	447
Orkney Islands	194
Perth & Kinross	215
Renfrewshire	256
Scottish Borders	195
Shetland Islands	192
South Ayrshire	202
South Lanarkshire	394
Stirling	188
West Dunbartonshire	250
West Lothian	231
Total	8,689

1.2.5 Sample Selection

The Royal Mail's small user Postcode Address File (PAF) was used as the sample frame for the address selection. The advantages of using the PAF are as follows:

• It has previously been used as the sample frame for Scottish Government surveys so previously recorded levels of ineligible addresses can be used to inform assumptions for 2022 sample design.
• It has excellent coverage of addresses in Scotland.
• The small user version excludes the majority of businesses.

The PAF does still include a number of ineligible addresses, such as small businesses, second homes, holiday rental accommodation and vacant properties. A review of the previous performance of individual surveys found that they each recorded fairly consistent levels of ineligible address for each local authority. This meant that robust assumptions could be made for the expected levels of ineligible addresses in the sample size calculations.

As the samples for the SHS, SHeS and SCJS have all been selected by the Scottish Government since 2012, addresses selected for any of the surveys are removed from the sample frame so that they cannot be re-sampled for another survey. This helps to reduce respondent burden. The addresses are removed from the sample frame for a minimum of four years.

The sample design specified in Section 1.2 for opt-in was implemented in three stages:

1. All primary sampling units (data zones on the islands, intermediate geographies elsewhere) were randomly allocated to one of four sets. One of these sets will be used in each year of fieldwork. This means that the sample is drawn from one quarter of PSUs each year. The sets were updated ahead of the 2021 sampling and this ensures that over four years of fieldwork (2021 to 2024) all addresses will have a non-zero probability of selection.

Table 6: Primary sampling units selected in 2021 knock-to-nudge/in-home sample

Health Board	PSUs in 2021 Sample	Total PSUs
Ayrshire and Arran	23	93
Borders	7	30
Dumfries and Galloway	10	40
Fife	26	104
Forth Valley	20	78
Grampian	33	132
Greater Glasgow and Clyde	64	257
Highland	20	79
Lanarkshire	40	160
Lothian	48	192
Orkney	7	29
Shetland	8	30
Tayside	23	92
Western Isles	9	36
Total	338	1,352

2. The required numbers of addresses for the main and child boost samples gave an overall total of addresses to sample for each stratum (local authorities). The required number of addresses for each stratum was then sampled from the sample frame of addresses in active PSUs. Systematic random sampling was used with addresses within PSUs ordered by urban-rural classification, SIMD rank and postcode.

3. Once the overall sample was selected, a proportion of the main sample addresses were randomly allocated to the biological module. One quarter of the target main adult sample was required to complete the biological module. To guard against a lower response rate to the different elements of the biological module, and to correct for inaccurate response assumptions in previous years, a proportion higher than the required one quarter of the adult sample (33% in 2022) were allocated to the biological module.

1.2.6 Selecting individuals within households

For the main sample, all adults aged 16 and over in responding households were eligible for interview. To ease respondent burden, for child interviews for both the main and the child boost samples a maximum of two children were interviewed at each household. If a household contained more than two children, then two were randomly selected for interview.

1.2.7 Selecting households at addresses with multiple dwellings

A small number of addresses have only one entry in the Postcode Address File (PAF) but contain multiple dwelling units. Such addresses are identified in the PAF by the Multiple Occupancy Indicator (MOI). To ensure that households within MOI addresses had the same probability of selection as other households, the likelihood of selecting addresses was increased in proportion to the MOI. At addresses with more than one dwelling unit fieldworkers have a programme to randomly select the household at which interviews should be sought. There are generally a few cases were the MOI on the PAF is inconsistent with the actual number of dwelling units. When this occurred, the fieldworkers recorded the information and a correction was made through the survey weighting.

1.2.8 Selecting individuals within households

For the main sample all adults aged 16 and over in responding households were selected for interview. To ease respondent burden, for child interviews for both the main and the child boost samples a maximum of two children were interviewed at each household. If a household contained more than two children, then two were randomly selected for interview.

1.3 Topic coverage

1.3.1 Introduction

Topics covered in the 2018 to 2022 surveys were agreed following a consultation carried out in 2016^[3]. Many of the topics and questions included in earlier years of the survey were included again to continue the time series. Questions on long COVID were introduced in 2021 and included again in 2022. The 2022 survey included the same rotating topics as the 2018 and 2016 surveys (see sections 1.3.3 and 1.3.4), with the exception that questions on chronic pain were included for the first time. As with previous years, the 2022 survey had a focus oncardiovascular disease (CVD) and its associated risk factors.

A report on the outcome of a public consultation about the content of the survey from 2018 is available from the Scottish Government website. This report outlines key changes to be made to the 2018-2022 surveys and other topics which would be considered if space became available.

A further review was conducted in 2022^[4]. This will inform changes to the survey from 2024 onwards.

1.3.2 Documentation

Copies of all the documents used in data collection are included in Appendix A. Full copies of the questionnaire documentation used in the main interview and biological module are also available at Scottish Health Survey. A summary of the main interview content and the content of the biological module is provided below.

1.3.3 Main interview

Information was collected at both the household and individual level. The content of the individual level interviews for all participants is summarised below. The topics a participant was asked depended both on their age and the sample type to which their address had been allocated. The age criteria for each topic are included in brackets following the topic name.

Content of the main 2022 interview

• Household questionnaire including household composition
• General health including unpaid caring (0+)
• Respiratory symptoms and cardiovascular disease (16+)
• Asthma (0+) – some questions asked of version A only
• Chronic Pain (0+)
• Physical activity adults (16+) and children (2-15)
• COVID-19 (0+)
• Eating habits children (2-15)
• Fruit and vegetables consumption (2-15)
• Smoking (18+)
• Passive smoking (0+)
• Drinking (18+)
• Dental health (16+)
• Employment and economic activity (16+)
• Education (16+)
• Self-reported/interviewer-administered measurements (0+)
• Ethnic background, religion and country of birth (0+)

Overview of topics included in SHeS adult self-completions

• Mental wellbeing
• Loneliness
• Sexual orientation
• Sex/trans status
• Veteran status
• Depression, anxiety, self-harm and suicide (only asked of those assigned to Version B – approximately a third of adults)

Overview of topics included in SHeS young adult self-completion booklets

• Mental wellbeing
• Alcohol
• Smoking
• Loneliness
• Sexual orientation
• Sex/trans status
• Depression, anxiety, self-harm and suicide (only asked of those assigned to Version B – approximately a third of adults)
• Veteran status

Overview of topics included in 13–15-year-olds self-completion booklets

• Mental wellbeing

Overview of topics included in 4–12-year-olds self-completion booklets

• Strengths and difficulties questionnaire (SDQ)

Version A households accounted for 62% of the main (core) sample. At these households the questionnaire included the core questions and the questions included in the Version A rotating module. In 2022, topics in the Version A rotating module included some additional questions on respiratory health.

Version B households accounted for the remaining 38% of the main (core) sample. At these addresses, participants were asked the core questions during the main interview, with a slightly longer self-completion module that included depression, anxiety, self-harm and attempted suicide questions.

A significant number of changes were made to the questionnaire content in advance of the 2018 survey based on the consultation that took place in Autumn 2016, with a summary of responses published in Spring 2017^[5]. These changes are discussed below and in the Scottish Health Survey: Report of Questionnaire Changes from 2018^[6].

In 2021 and 2022, questions on COVID-19 vaccinations and long COVID were included to monitor the continued effects of the pandemic on the health of those living in Scotland.

In 2022, questions were included to establish the prevalence and effects of chronic pain^[7] among adults and children living in Scotland.

The full question wording of all the questions used in 2022 can be found at Scottish Health Survey.

1.3.4 Self-completion questionnaire

Participants aged 13 and over and parents of participants aged between 4 and 12 were asked to fill in a self-completion booklet during the interview. In all, four different booklets were administered. The version completed was dependent on the age of the participant.

The booklet for young adults aged 16-17 included questions on smoking and drinking behaviour (instead of these being asked as part of the CAPI interview). Interviewers also had the option of administering this young adults self-completion for those aged 18-19 if they felt that it would be more appropriate.

A question on previous service in the UK Armed Forces was added to the adult and young adult self-completion booklets in 2022.

For the wording of the questions in full, see the adult or young adult self-completion booklet listed at Scottish Health Survey.

Paper questionnaire booklets and web-based self-complete questionnaires contained the following topics in the 2022 survey:

Adults

(Versions A & B) General Health Questionnaire (GHQ12), Warwick Edinburgh Mental Well-being scale (WEMWBS), loneliness, sexual orientation, sex, trans status and previous UK Armed Forces service.

(Additional questions in version B) - depression, anxiety, self-harm and attempted suicide.

Young adults

Smoking (including use of e-cigarettes), drinking, GHQ12, WEMWBS, loneliness, sexual orientation, sex, trans status and previous UK Armed Forces service.

13-15 year olds GHQ12 and WEMWBS.

Parents of 4-12 year olds

Strengths and Difficulties questionnaire (SDQ) (designed to detect behavioural, emotional and relationship difficulties in children).

1.3.5 Height and weight

Standardised interviewer-administered height and weight measurements were reintroduced as part of in-home interviews in 2022. As the interviewer panel was being built back up and additional training, reaccreditations and/or equipment were needed, some face-to-face interviews required the collection of self-reported height and weight data. For interviews conducted by telephone, no height and weight measurements or biological measures could be taken. Participants were asked to estimate their own height and weight during these interviews and for any face-to-face interviews where accreditations for standardised measurements had not yet taken place.

1.3.6 Biological module

As highlighted previously, a sub-sample (around 40%) of main core sample addresses, adults (aged 16 and over) were selected to complete the biological module. Since 2012, specially trained interviewers have been collecting the measurements and samples which were collected by nurses in previous years (1995 to 2011). This was not possible in 2021, therefore, no objective biological measurements were collected. These measurements were reintroduced in 2022 as the panel of suitably trained and accredited interviewers was built back up again.

Participants in this sample were asked a set of questions about depression, anxiety, suicide attempts and self-harm (taken from the Adult Psychiatric Morbidity Survey) as part of their self-completion questionnaire. These questions were previously completed by the respondent using a computer-assisted self-completion approach (CASI) directly on to the interviewer's laptop.

1.4 Fieldwork procedures

1.4.1 Advance letters

Each sampled address was sent an advance letter that introduced the survey and, for the in-home samples, to let the resident know that an interviewer would be calling to seek permission to interview. A number of versions of the advance letter were used in 2022; one for the Core version A addresses, one for Core version B addresses (with the biological module), and one for child boost addresses. There was a version of each of these letters for each organisation conducting interviews (ScotCen and ONS), as well as for child boost opt-in and Core knock-to-nudge and in-home samples. A copy of the survey leaflet was included with every advance letter. The survey leaflet introduced the survey, described its purpose in more detail and included some summary findings from previous surveys.

For copies of the advance letters and survey leaflet, see the documents listed in Appendix A.

1.4.2 Making contact

Initial contact for both samples was made via the advance letter. For the child boost opt-in sample, this letter provided instructions for taking part which involved contacting ScotCen via an online opt-in portal, the survey email address and/or the survey freephone number. Additional information was then sent by post to participants who opted in, which was followed by interviewer telephone contact to arrange a time to complete the interview.

The knock-to-nudge and in-home approaches differed in that interviewers were able to visit respondent's homes to attempt to gain agreement to participate in the survey, some of which continued to be conducted by telephone but which were increasingly done in-home. At initial contact, the interviewer established the number of dwelling units (DUs) and/or households (HHs) at an address and made any necessary selections (see Section 1.2.7).

The interviewer then attempted to make contact with each household. In the main sample they attempted to interview all adults (up to a maximum of ten) and up to two children aged 0-15 (see Section 1.2) from the household. At child boost sample households, interviewers first screened for children aged 0-15. In those households where children were present up to two children were randomly selected for interview. Interviewers obtained the verbal consent of both the parent/guardian and the child before commencing the interview.

1.4.3 Collecting data

Interviewers used computer assisted personal (CAPI) interviewing for interviews done in-home and computer assisted telephone interviewing (CATI) for the telephone interviews.

At each co-operating eligible household (across all sample types), the interviewer first completed a household questionnaire, with information collected from the household reference person^[8] or their partner wherever possible. This questionnaire obtained basic information (including date of birth and relationship to other household members) about all members of the household, regardless of age and whether they were eligible to take part in the interview. The computer assisted personal/telephone interviewing (CAPI) program then created individual questionnaires for each eligible participant in the household.

Where possible an individual interview was then conducted with all eligible adults and up to two children in a household. In order to reduce the amount of time spent in the home, interviews could be carried out concurrently.

In addition to an advance letter and general survey leaflet, participants were also given a more detailed leaflet describing the contents and purpose of the interview, and what will happen to information they provide (including a link to the Privacy Notice on the Scottish Government's website).

A separate version of this leaflet was used for children in both main and child boost households. Parents at child boost addresses were also provided with a leaflet containing background information on the survey. Copies of all the participant leaflets used in the survey are included in Appendix A.

1.4.4 Interviewing and measuring children

Children aged 13-15 were interviewed directly by interviewers, after verbal consent had been obtained from both the child and their parent or guardian. Interviewers were instructed to ensure that the child's parent or guardian was present throughout the interview. Information about younger children (aged 0-12) was collected directly from a parent or guardian. Whenever possible, younger children were present while their parent or guardian answered questions about their health. This was partly because the interviewer had to take the child's height and weight measurements (where possible), but it also ensured that the child could contribute information where appropriate (for example, about physical activity done during school time).

1.4.5 Feedback to participants

If participants wished, interviewers recorded their height and weight measurements within their information leaflet. Participants kept the information leaflet and thus had a record of their height and weight, if they wished.

Participants eligible for the biological module were given an additional document; the biological measurement record card. If participants had their waist measurement and blood pressure taken, then interviewers recorded their results on this card (if the participant wished). As before, participants could keep this measurement record card and thus had a note of their measurements.

For the biological module, interviewers were issued with a set of guidelines to follow when commenting on participants' blood pressure readings. If the participant's blood pressure was mildly raised, they were instructed to advise the participant to contact their GP within 2 months. If the participant's blood pressure was moderately raised, they were instructed to advise the participant to contact their GP within 2 weeks. Finally, if the participant's blood pressure reading was considerably raised, interviewers advised the participant to visit their GP within 5 days and interviewers were instructed to contact the survey doctor at the earliest opportunity. The survey doctor would then phone the participant and advise them to contact their GP as soon as possible.

1.5 Fieldwork quality control and ethical clearance

1.5.1 Training interviewers

Interviewers new to SHeS were fully briefed on the survey's content and procedures. Interviewers were supervised by an interviewer supervisor during the early stages of their work to ensure that interviews were administered correctly, and protocols were followed.

Interviewers that had worked on SHeS in previous years attended a refresher briefing ahead of the launch of the new survey year and were refreshed on any additional in-home processes when this was introduced. This ensured that they were aware of changes to survey content and procedures for 2022.

Interviewers interested in administering the biological module were initially screened for suitability. Minimum competency levels were set and only interviewers that met the set criteria were invited to training and accreditation sessions.

Full sets of written instructions, covering both survey procedures and measurement protocols, were provided to interviewers (measurement protocols are available on request from ScotCen).

1.5.2 Checking interviewer and measurement quality

A large number of quality control measures were built into the survey at the data collection stage and thereafter, to monitor the quality of interviewer performance.

Quality checks were carried out at 10% of productive households. These recalls checked with the participants that interviewers had followed the correct survey procedures when conducting the interview.

In addition to the above quality checking procedure, the computer program used by interviewers had in-built soft checks (which can be suppressed) and hard checks (which cannot be suppressed) associated with particular interview questions. When uncommon or unlikely answers were entered, or answers outside a predetermined range, these checks were triggered and appear as a warning message on the interviewers' laptop. The interviewer is either encouraged to double-check the entered response (a soft-check) or asked to change it (a hard-check). For example, when young children were weighed by having an adult hold them; the weight of the adult on their own was entered into the computer followed by the combined weight of the infant and adult. A hard check was used to ensure that the weight entered for the adult alone did not exceed the weight of the infant and adult combined.

Soft-checks were similar to hard-checks, however they could be suppressed. For example, soft-checks were applied to height measurements; if an interviewer entered a respondent's height to be in excess of 1.93 metres (6 feet 3 inches), a message appeared asking the interviewer to confirm that this entry was correct. The interviewer could suppress the soft-check once they had confirmed that the height entry was not a mistake.

1.5.3 Ethical clearance

Ethical approval for the 2022 survey was obtained from the Health and Care Research Ethics Committee for Wales (REC reference number: 17/WA/0371).

1.6 Survey response

1.6.1 Introduction

This section presents the fieldwork outcomes for the sampled addresses. Survey response is an important indicator of survey quality as non-response can introduce bias into survey estimates. Standardised outcome codes (based on an updated version of those published in Lynn et al, 2001^[9]) for survey fieldwork were applied across the SHeS, SHS and SCJS. This enables consistent reporting of fieldwork performance and effective comparison of performance between the surveys.

1.6.2 Household response

Tables 1.1a and 1.1b show a detailed breakdown of the SHeS response for sampled addresses in 2022, which are reported separately for the knock-to-nudge and in-home samples. Addresses with unknown eligibility have been allocated as eligible and ineligible proportional to the levels of eligibility for the remainder of the sample. This approach provides a conservative estimate of the response rate as it estimates a high proportion of eligible cases amongst addresses with unknown eligibility.

At each selected household in the main sample, all adults and a maximum of two children were eligible for interview. When considering the household response rate, households classed as "responding" were those where at least one eligible person opted-in/consented to interview and was interviewed. The tables show that for the main knock-to-nudge sample, 40.5% of eligible households were classed as responding whilst for in-home households this proportion was 37.6%. All individual interviews were completed at 33.2% of knock-to-nudge and 31.1% of in-home households.

For the child boost opt-in sample, 7.3% of eligible households contacted opted in and all individual interviews were complete at 82.0% of households. In the child boost CHI-screened in-home sample, 80.3% of issued addresses were deemed eligible and all individual interviews were complete at 46.6% of these households.

Table 1.2a shows that across Heath Boards, the percentage of combined knock-to-nudge/in-home sample households where at least one eligible person was interviewed ranged from 27.1% (Fife) to 63.2% (Orkney Islands). Fully cooperating households were those where all eligible individuals were interviewed. This varied between 27.2% in Forth Valley to 53.6% in the Orkney Islands. The definition of a fully cooperating household changed in 2012 and is therefore not comparable with fully cooperating figures prior to this.

Table 1.2b shows the household response rate for eligible addresses in the opt-in child boost sample by Health Board. This varied from 2.1% (Scottish Borders) to 13.1% (Forth Valley). Note that the bases for child boost response rates were quite low in a number of areas (for example 48 eligible households in the Borders and 70 in Dumfries and Galloway).

Table 1.2c shows that across Heath Boards, the percentage of in-home child boost households where at least one eligible person was interviewed ranged from 27.8% (Dumfries and Galloway) to 63.3% (Highland). Fully cooperating households were those where all eligible children were interviewed. For most Health Boards, this figure matched that for at least one eligible person being interviewed and thus the range varied in the same manner (27.8% in Dumfries and Galloway to 63.3% in Highland).

Table 1.3a shows that across Local Authorities, the percentage of combined main sample households where at least one eligible person was interviewed ranged from 27.1% (Fife) to 63.2% (Orkney Islands). Fully cooperating households varied between 22.0% (Fife) and 53.6% (Orkney Islands).

Table 1.3b shows the household response rate for eligible addresses in the opt-in child boost sample by Local Authority. This varied from 1.7% (Dumfries and Galloway) to 15.8% (Falkirk). Note that the bases for child boost response rates were particularly low in a number of areas (for example 25 eligible households in Clackmannanshire and 43 in Moray).

Table 1.3c shows that across Local Authorities, the percentage of child boost in-home households where at least one eligible child was interviewed ranged from 13.3% (East Ayrshire) to 81.8% (Argyll and Bute). Figures were almost identical for fully cooperating households. Again, the small base sizes should be noted. Tables 1.1a – 1.3c

1.6.3 Individual response for adults

Overall, there were 4,394 adult responses (888 from the knock-to-nudge sample and 3506 from in-home) to SHeS 2022.

The adult response rate in 2022 was calculated based on the number of eligible households. This was undertaken by dividing the number of individual adult interviews by the number of eligible adults in productive households. The total estimated number of adults from sampled addresses eligible for interview is referred to as the "set" sample. For 2022, the set sample of adults for the combined knock-to-nudge and in-home sample was 5,011.

Table 1.9 shows that the age distribution of respondents to the main combined sample was generally older than the population as a whole. For men, 53% of core opt-in respondents were aged 55 or older compared with 39% of the male population as a whole. There were similar but smaller differences for women, with 51% of female respondents aged 55 or older compared with 42% of the female population as a whole.

Tables 1.4a and 1.5

1.6.4 Individual response for children (0-15)

Interviews were undertaken with 1,764 children aged 0 to 15, with 158 interviews taking place as part of the main knock to nudge sample, 557 as part of the main in-home sample, 361 as part of the opt-in child boost sample and 688 as part of the CHI-screened in-home child boost sample.

In order to calculate the response rate for children, the number of eligible children in opted-in or participating households was calculated. Tables 1.4a, 1.4b and 1.4c show that overall response rates for the child boost opt-in sample and the child boost in-home sample were similarly high whereas it was a lower for children in the main sample (99.7% and 99.3% for the child boost opt-in and in-home samples respectively and 90.4% for children in the main sample).

Tables 1.4a and 1.4c

1.7 Weighting the data

1.7.1 Introduction

This section presents information on the weighting procedures applied to the survey data. Since 2012 the weighting for SHeS has been undertaken by the Scottish Government rather than the survey contractor (as had previously been the case), but the methodology applied was largely consistent with that of the 2008 to 2011 sweeps of the survey. The procedures for the implementation of the weighting methodology were developed by the Scottish Government working with the Methodology Advisory Service at the Office for National Statistics^[10].

To undertake the calibration weighting the ReGenesees Package for R was used. Within this, to execute the calibration, a raking function was implemented.

1.7.2 Main adult weights

The main adult weight is applicable for all adults interviewed as part of the main sample. There were six steps to calculating the overall adult weights. These were as follows:

1) Address selection weights (w1)

The address selection weights were calculated to compensate for unequal probabilities of selection of addresses in different survey strata. For the main sample there were 32 strata (one for each local authority).

2) Dwelling unit selection weights (w2)

The Multiple Occupancy Indicator (MOI) for the PAF was used to ensure that if there were multiple dwelling units at a single address point then they would have the same selection probability as individual addresses. However, there are likely to have been some cases where the MOI was incorrect. In face-to-face fieldwork, interviewers record where an MOI is different from PAF when visiting a property. This is not possible via the telephone survey and so the information provided by PAF was assumed to be correct. Therefore w2 is effectively 1 for all households.

3) Household selection weights (w3) Similarly to w2, within a very small number of dwelling units, fieldworkers usually find multiple households, of which only one is selected for participation. Again, due to data collection via the telephone rather than face-to-face, it is not possible to correct for this, therefore w3 was effectively taken as 1 for all households.

4) Calibrated household weights (w4)

The three selection weights were combined (w1*w2*w3) before the household calibration stage. This combined weight was applied to the survey data to act as entry weights for the calibration. The execution of the calibration step then modified the entry weights so that the weighted total of all members of responding households matched the population totals for Health Boards, Scotland-level population totals for age/sex breakdown, and the population within each SIMD quintile. The population totals that were used were the National Records of Scotland's (NRS) mid-2021 estimates for private households.

5) Adult non-response weights (w5)

All adults within selected households were eligible for interview, but within responding households not all individuals completed an interview. The profiles of household members that did not complete the interview were different from those that did. Information on all individuals within responding households was available through information gathered as part of the household interview. This allowed the differential response rates for individuals within households to be modelled using logistic regression to calculate a probability of responding based on their profiles. The logistic regression was only applicable for households containing more than one adult since households consisting of only one adult either responded to the household and individual interviews or did not respond at all.

The following variables were considered for inclusion in the model:

• Health Board
• Age/sex
• Number of adults in the household
• Employment status of household reference person
• Presence of a smoker in the household
• Marital status
• Tenure
• Urban/rural classification
• Access to a car
• Located within SIMD15 area
• Frequency of eating meals together

Through running backwards and forwards selection procedures for the logistic regression the following variables were included in the final model:

• Health Board
• Age/sex
• Number of adults in the household
• Located within SIMD15 area
• Marital status
• Frequency of eating meals together
• Access to a car

The final logistic regression model was then used to calculate the probability of response for all individuals that did respond. The adult non-response weight (w5) was then calculated as the reciprocal of this probability:

For households of only one adult the non-response weight was one.

6) Individual calibration and final adult weight (int22wt)

The household (w4) and non-response (w5) were combined (w4*w5) and applied to the survey data prior to the final stage of calibration weighting which matched weighted totals for the survey data to the NRS 2021 mid-year population estimates for Health Boards, age/sex distribution at Scotland level and age/sex distribution for the Glasgow and Greater Clyde Health Board.

Table 7: 2021 Mid-year population estimates for private households in Scotland by Health Board

Health Board	Adults	Children	Total
Ayrshire & Arran	304,631	59,771	364,402
Borders	96,182	18,675	114,857
Dumfries & Galloway	124,078	22,808	146,886
Fife	300,187	63,441	363,628
Forth Valley	247,695	51,023	298,718
Grampian	473,320	99,893	573,213
Greater Glasgow & Clyde	959,472	195,943	1,155,415
Highland	265,836	50,244	316,080
Lanarkshire	541,685	117,215	658,900
Lothian	738,118	151,098	889,216
Orkney	18,788	3,508	22,296
Shetland	18,676	4,058	22,734
Tayside	341,617	65,945	407,562
Western Isles	22,241	4,050	26,291
Total	4,452,526	907,672	5,360,198

Table 8: 2021 Mid-year population estimates for private households in Scotland by SIMD Quintile

SIMD Quintile	Total population
1 – 20% most deprived data zones	1,040,303
2	1,037,947
3	1,056,098
4	1,132,570
5 – 20% least deprived data zones	1,093,280
Total	5,360,198

Table 9: 2021 Mid-year population estimates for private households in Scotland by age group

Age group	Male	Female	Total
0-4	130,676	123,683	254,359
5-9	150,295	142,190	292,485
10-15	183,843	176,986	360,829
16-24	258,071	242,178	500,249
25-34	368,141	373,159	741,300
35-44	335,724	351,250	686,974
45-54	348,741	375,304	724,045
55-64	365,713	392,521	758,234
65-74	282,117	308,749	590,866
75+	192,635	258,222	450,857
Total	2,615,956	2,744,242	5,360,198

1.7.3 Biological module weights

A similar process was applied to derive the weights for the biological module. This is outlined below.

1) Address selection weight (bw1)

New address selection weights were calculated using the same process as described for w1.

2) Dwelling unit (w2) and household selection weights (w3)

The dwelling unit and household selection weights from the main adult weight were applied as above.

3) Calibrated household weight (bw4)

The three selection weights were combined (bw1*w2*w3) and applied to the survey data before the household calibration was run so that survey data matched the population totals for Health Boards, Scotland-level age/sex breakdowns, and the population within SIMD15 areas.

4) Adjustment for biological module selection (bw5)

33% of the main sample was allocated to the biological module. To incorporate this probability of selection a correction was applied to the calibrated household weight (bw4). The correction was:

5) Application of adult non-response (w5)

For within household non-response, the non-response weight (w5) calculated for all households was also applicable for the biological module.

6) Final calibration for biological module (bio22_wt)

The household (bw4), biological sample correction (bw5) and adult non-response (w5) weights were combined (bw4*bw5*w5) and applied to the survey data.

For the final stage of biological module weighting the weighted totals for the survey data were calibrated to match the NRS 2021 mid-year population estimates for private households for Health Boards, age/sex distribution at Scotland level. However, due to the low sample size for the module a number of the categories had to be collapsed. In terms of Health Boards, all areas except for Grampian, Greater Glasgow and Clyde, Lanarkshire and Lothian were grouped together. For the age groups, the lowest two age groups were combined.

1.7.4 Biological measurements weight

As the biological measurements were reintroduced gradually partway through the fieldwork year, not all of those taking part in the other parts of the biological module (i.e. the questionnaire elements) were able to provide measurement data. This means the sample providing measurement data and the sample providing other biological module data were potentially different. As such, the main biological module weight was not deemed sufficient to correct any potential bias in the measurement data. For this reason, a new weight was required for 2022 for those individuals that were selected for the biological module and provided biological measurements. The process for deriving weights for individuals that did provide measurements was similar to that for the main adult weights. This process is outlined below:

1) Address selection weight (bw1)

New address selection weights were calculated using the same process as described for w1.

2) Dwelling unit (w2) and household selection weights (w3)

The dwelling unit and household selection weights from the main adult weight were applied as above.

3) Calibrated household weight (bw4)

As there was no Health Board boost, the calibrated household weights (w4) were applied from above.

4) Adjustment for biological module selection (bw5)

33% of the main sample was allocated to the biological module. To incorporate this probability of selection a correction was applied to the calibrated household weight (bw4). The correction was:

5) Application of adult non-response (w5)

For within household non-response, the non-response weight (w5) calculated for all households was also applicable for the biological module.

6) Non-response weight for biological module interview

Not all adults who responded to the main section of the interview responded to the biological module. Similarly, not all adults selected for the biological module provided biological/physical measurements. Using the information collected for the respondent in the biological module interview the likelihood of providing biological/physical measurements was modelled with logistic regression.

The following variables were considered for inclusion in the model:

• Health Board
• Age/sex
• Number of adults in the household
• Employment status of household reference person
• Presence of a smoker in the household
• Marital status
• Tenure
• Urban/rural classification
• Access to a car
• Located within SIMD15 area
• Frequency of eating meals together
• Self-assessed general health
• Whether done gardening/DIY/building work in the past 4 weeks
• Whether has longstanding illness
• Highest achieved qualification
• Level of physical activity
• Economic activity (including if retired)
• Ever had high blood pressure
• Whether smokes cigarettes or drinks nowadays
• Number of natural teeth
• Whether done any housework in past 4 weeks

Through running backwards and forwards selection procedures for the logistic regression the following variables were included in the final model:

• Health Board
• Age/sex
• Number of adults in the household
• Located within SIMD15 area
• Marital status
• Access to a car
• Urban/rural classification
• Whether drinks nowadays
• Economic activity – working or retired

The final logistic regression model was then used to calculate the probability of response for all individuals that did respond. The adult non-response weight (w5) was then calculated as the reciprocal of this probability:

7) Final calibration for biological module (biophy22_wt)

The household (bw4), biological sample correction (bw5) and adult non-response (w5) weights were combined (bw4*bw5*w5) and applied tothe survey data.

For the final stage of biological module weighting the weighted totals for the survey data were calibrated to match the NRS 2021 mid-year population estimates for private households for Health Boards, age/sex distribution at Scotland level.

1.7.5 Non-biological module weights (Version A)

A weight titled "Version A" was calculated for the individual respondents in the main sample that were not selected for the biological module. The following steps were followed to derive the weight:

1) Address selection weight (bw1)

As derived in the first step of the biological module weight.

2) Dwelling unit (w2) and household selection weights (w3)

The dwelling unit and household selection weights from the main adult weight were applied as above.

3) Calibrated household weight (bw4)

As derived for the biological module.

4) Adult non-response weight (w5)

For within household non-response, the non-response weight (w5) calculated for all households was also applicable for the biological module.

5) Final calibration for Version A weight (verA22wt)

The household (bw4) and adult non-response (w5) weights were combined (bw4*w5) and applied to the survey data. As was the case with the main adult weight and biological module weight, the weighted totals for the survey data were calibrated to match the NRS 2021 mid-year population estimates for private households for Health Boards, age/sex distribution at Scotland level.

1.7.6 Overall child weights

An overall child weight was derived for child responses from the main sample and from the child boost combined. Separate logistic regression non-response weights were not required for the child samples as the response rate for children within cooperating households was sufficiently high. The weighting steps are shown below. Steps (1) and (2) followed the same process as described in 1.7.2 above.

1) Address selection weight for main sample and child boost combined (cw1)

2) Dwelling unit (cw2) and household (cw3) selection weights

3) Selection of children within each household (cw4)

A maximum of two children were eligible for interview in each household. To ensure that children in larger households were not under-represented in the final sample the following child selection weight was calculated for households with more than two children to compensate for the probability of selection:

For households with two or fewer children cw4=1.

4) Calibration for child interview weight (cint22wt)

The address selection (cw1), dwelling unit (cw2), household (cw3) and child selection weights (cw4) were combined (cw1*cw2*cw3*cw4) and applied to the survey data. The weighted totals for the survey data were calibrated to match the NRS 2021 mid-year population estimates for private households for Health Boards, age/sex distribution at Scotland level.

Weights were also created specifically for within household analysis, comparing children's characteristics with those of their parents. As data were only collected with respect to both children and adults in the core sample, these weights were only created for children at core sample addresses. They were created in a similar fashion to that described for the whole of the overall child weights.

1.7.7 Combined weights

A number of different combinations of annual sweeps have been produced to allow the analysis of combined datasets. Due to disruption to the survey at the onset of the pandemic, the survey data collected in 2020 was published as experimental statistics and was not comparable with the time series^[11]. This data has not been included in the survey trends or the combined years' analysis.

Weight name	Purpose of combined weight
int18192122wt	For analysis of 2018, 2019, 2021 and 2022 combined adult data
cint18192122wt	For analysis of 2018, 2019, 2021 and 2022 combined child data
bio18192122wt	For analysis of 2018, 2019, 2021 and 2022 combined depression, anxiety, suicide and self-harm data
biophy18192122wt	For analysis of the bio measurements (blood pressure, hypertension and saliva)
cmint18192122wt	For analysis of 2018, 2019, 2021 and 2022 combined child data core sample only (for within household analysis)
cva18192122wt	For analysis of 2018, 2019, 2021 and 2022 combined version A child module data
vera18192122wt	For analysis of 2018, 2019, 2021 and 2022 combined version A adult module data
int2122wt	For analysis of 2021 and 2022 combined adult data
cint2122wt	For analysis of 2021 and 2022 combined child data
bio2122wt	For analysis of 2021 and 2022 combined depression, anxiety, suicide and self-harm data
cmint2122wt	For analysis of 2021 and 2022 combined child data core sample only (for within household analysis)
int1822wt	For analysis of 2018 and 2022 combined adult data
cint1822wt	For analysis of 2018 and 2022 combined child data
vera1822wt	For analysis of 2018 and 2022 combined version A adult module data
cva1822wt	For analysis of 2018 and 2022 combined version A child module data
hh1822wt	For analysis of 2018 and 2022 combined household level data

In each case, the calculation of the weights followed the same procedure. The pre-calibration weights which had already been calculated for the individual years (which take into account selection weighting and (except for the child weights) non-response weighting) were combined and calibrated to Health Board and age/sex 2021 population totals for private households.

1.8 Data analysis and reporting

SHeS is a cross-sectional survey of the population. It examines associations between health status, personal characteristics and behaviour. However, such associations do not necessarily imply causality. In particular, associations between current health status and current behaviour need careful interpretation, as current health may reflect past, rather than present, behaviour. Similarly, current behaviour may be influenced by advice or treatment for particular health conditions.

1.8.1 Reporting age variables

Defining age for data collection

A considerable part of the data collected in SHeS 2022 is age specific, with different questions directed to different age groups. During the interview the participant's date of birth was ascertained. For data collection purposes, a participant's age was defined as their age on their last birthday before the interview.

Age as an analysis variable

Age is a continuous variable, and an exact age variable on the data file expresses it as such (so that, for example, someone whose 24th birthday was on January 1, 2022 and was interviewed on October 1, 2022 would be classified as being aged 24.75).

The presentation of tabular data involves classifying the sample into year bands. This can be done in two ways, age at last birthday and 'rounded age', that is, rounded to the nearest integer. In this report, all references to age are age at last birthday.

Some of the adult data included in the 2022 report have been age-standardised to allow comparisons between groups after adjusting for the effects of any differences in their age distributions. Further information on age standardisation can be found in chapter 2 of this report.

1.8.2 Standard analysis breakdowns

Scottish Index of Multiple Deprivation (SIMD)

The analysis of 2022 data was based on the most recent version of the Scottish Index of Multiple Deprivation (SIMD), published in 2020^[12].It is based on 38 indicators in seven individual domains of current income, employment, housing, health, education, skills and training, geographic access to services and crime. SIMD is calculated at data zone level, enabling small pockets of deprivation to be identified. The data zones are ranked from most deprived (1) to least deprived (6,976) on the overall SIMD index. The result is a comprehensive picture of relative area deprivation across Scotland. The index was divided into quintiles for the presentation of analysis within this report. The full index is not available on the archived dataset due to concerns about its potential for identifying individual respondents or households.

1.8.3 Design effects and true standard errors

SHeS 2022 used a partially clustered, stratified multi-stage sample design. In addition, weights were applied when obtaining survey estimates. One of the effects of using the complex design and weighting is that standard errors for survey estimates are generally higher than the standard errors that would be derived from an unweighted simple random sample of the same size. The calculations of standard errors shown in tables, and comments on statistical significance throughout the report, have taken the clustering, stratification and weighting into account. The ratio of the standard error of the complex sample to that of a simple random sample of the same size is known as the design factor. Put another way, the design factor (or 'deft') is the factor by which the standard error of an estimate from a simple random sample has to be multiplied to give the true standard error of the complex design. The true standard errors and defts for SHeS 2022 have been calculated using a Taylor Series expansion method. The deft values and true standard errors (which are themselves estimates subject to random sampling error) are shown in Tables 1.10a to 1.18d for selected survey estimates presented in the main report. Tables 1.10a – 1.18d