Scottish Crime and Justice Survey 2012/13: Drug Use

1 Introduction

1.1 Introduction

The Scottish Crime and Justice Survey (SCJS) is a large-scale survey measuring adults' experience and perceptions of crime in Scotland. The main aims of the SCJS are to:

• Examine trends in the number and nature of crimes in Scotland over time, providing a complementary measure of crime compared with police recorded crime statistics;
• Examine the varying risk of crime for different groups of adults in the population;
• Provide a valid and reliable measure of adults' experience of crime, including services provided to victims of crime;
• Collect information about adults' experiences of, and attitudes to, a range of crime and justice related issues.

The main survey is based on face-to-face interviews which were conducted in respondents' homes between April 2012 and March 2013. In 2012/13, 12,035 respondents completed the main survey. Respondents were also asked to answer a separate self-completion module on more confidential and sensitive issues, including drug taking, partner abuse, sexual victimization and stalking. This self-completion section was completed by 10,235 respondents (85% of all respondents).

This report presents the key findings about illicit drug use collected through the self-completion section of the survey. A Technical Report and User Guide are also available.^[2] The SCJS is the only source of information on self-reported illicit drug use among the general adult population of Scotland as a whole.^[3]

The report has two substantive chapters considering: the prevalence of illicit drug use in Scotland exploring trends in self-reported drug use and experiences of those who reported drug use Scotland. The report examines self-reported illicit drug use by adults aged over 16 using three time periods: in the last month, in the last year and ever.

1.2 Drug Use

The main aim of the self-completion illicit drug use questionnaire was to establish whether adults aged 16 or over reported illicit drug use either at some point in their lives, in the last year and in the last month. Sixteen drugs were included in the 2008/9 and 2009/10 surveys with five 'new' drugs'^[4] added in the SCJS 2010/11 (BZP, GBL, khat, synthetic cannabinoids and mephedrone) and one new drug added in 2012/13 (salvia divinorum). In the SCJS 2012/13, respondents were asked whether they had used 18 illicit drugs or groups of illicit drugs. The list of drugs included a fictitious drug 'semeron' and eleven respondents who said they had taken this drug were removed from the analysis. The list of drugs also included six new drugs. Respondents were asked whether they had used a group of five new drugs (BZP, GBL, Synthetic Cannabinoids, Khat or Salvia Divinorum) and separately whether they had used the new drug mephedrone. Those who had used any types of drugs were then asked a series of follow-up questions. Further details of the questionnaire content can be found in Annex 2 (section A.2.2).

1.3 Methodology

The SCJS 2012/13 fieldwork was conducted between April 2012 and March 2013. The design of the 2012/13 SCJS remains broadly similar to the 2008/09 to 2010/11 survey designs. A change to design was made for the SCJS 2012/13 which saw the survey move to a single stage unclustered sample design. The SCJS used a random probability sample method and was designed to be representative of the population of households in Scotland and adults aged 16 or over living in those households. The SCJS was sampled from private residential addresses in Scotland using the Royal Mail Postcode Address File (PAF). One adult aged 16 years or over per household was then randomly selected for interview. As the survey only included private residential addresses, it is acknowledged that it can underrepresent key groups who are likely to use illicit drugs (section 1.4.2).

Questions on illicit drug use were included in the self-completion section of the questionnaire, which was undertaken at the end of the main SCJS interview. Respondents were handed the interviewer's tablet computer and guided by the interviewer through a series of practice questions which explained how to use the computer. Where respondents were unable or unwilling to use the tablet computer themselves, interviewers administered the interview, showing the respondent the screen and helping them to input their answers. Participation was voluntary, with 10,235 (85%) of the 12,050 respondents to the main survey completing the self-completion questionnaire. Non-response was higher among adults aged 60 and over (see Annex 2 - section A.2.5).

A more detailed explanation of the methodology for the survey can be found in the SCJS 2012/13 technical report.^[5]

The data in this report has been weighted so that it is representative of the population (see Annex A.2.7 for information on weighting).

1.3.1 Statistical significance

A range of tests for statistical significance in the report were carried out using the Pearson chi-square test in SPSS. All significant associations in the report were found to be statistically significant at the p < 0.001 level. Tests for strength of association were carried out using Phi and Cramer's V tests in SPSS.

The assessments of statistical change over time which are presented in this report use estimated confidence intervals around survey results rounded to one decimal place to examine whether the change is statistically significant. The estimated confidence intervals used in these tests use generic SCJS design factors of 1.3 for 2012-13 and 1.5 for earlier surveys. More detail on the derivation of these design factors is available in Annex 4 of the Scottish Crime and Justice Survey 2012/13: Main Findings report. Statistically significant changes are highlighted in bold in tables in this report. Changes stated between previous sweeps of the SCJS and the SCJS 2012/13 represent a decrease or increase in percentage points.

1.4 Data Strengths and Limitations

1.4.1 Data strengths

The SCJS Drug Use survey is the best source of data available on prevalence of illicit drug use in the general adult population of Scotland. It is also the primary data source available on the prevalence of cocaine use in Scotland.

1.4.2 Data limitations

Under-reporting and under-representation of illicit drug use is a main concern of this survey. It is likely that there will be an under-representation of some groups who take drugs. In part, this will be due to the fact that some people who use drugs may live in accommodation not covered by a survey of private households (such as the SCJS) including, for example, hostels, prisons and student halls of residence. The survey is likely to under-represent those with the most problematic or chaotic drug use, some of whom may live in accommodation previously described and some of whom may live in private households covered by the survey, yet they may be rarely be at home or be unable to take part in an interview due to the chaotic nature of their lives.

Despite using Computer Assisted Self-completion Interviewing (CASI) for this module, it is likely there will be a certain amount of underreporting of illicit drug use among survey respondents. Illicit drug use is an illegal activity and as such some individuals may have felt uncomfortable reporting that they have taken illicit drugs, despite reassurances about confidentiality and anonymity.

Questions cover past use over varying periods (ever, in the last year and in the last month) and it is possible that some respondents may simply forget occasional uses of a certain drug, particularly if they last took it a long time ago. While under-reporting of drug use on surveys such as the SCJS is almost certain, it should be noted that the issues discussed above are unlikely to apply equally across all types of drugs. While a survey such as the SCJS is likely to provide an insight into the more commonly used drugs, in particular cannabis, it may be less effective in providing information for some of the Class A drugs such as opiates or crack cocaine, where a sizeable number of those using these drugs may be concentrated in small sub-groups of the population not covered by the survey (Smith and Flatley, 2011).

It is also recognised that some people may report taking particular drugs when they have not actually done so. Respondents were therefore asked whether they had ever taken a fictitious drug 'semeron'. Eleven respondents reported having ever taken semeron and these respondents have been excluded from the analysis in this report (making the overall sample 10,224 respondents).

Percentage figures in the report are displayed to one decimal place. However, it should be noted that there is in fact a range of uncertainty around all survey estimates and that the statistical testing conducted to assess change and differences between survey results (as outlined in section 1.3.1) are based on confidence intervals around survey estimates rounded to one decimal.

1.5 Classification of drugs

The Misuse of Drugs Act 1971 classifies illegal drugs into three categories (Class A, B and C) according to the harm they cause. The 17 drugs or groups of drugs that respondents were asked about and their classification under the Act are:

• Class A, including cocaine, crack, crystal meth, ecstasy, LSD, magic mushrooms, heroin, methadone and amphetamines (if prepared for injection);^[6]
• Class B, including amphetamines (in powdered form) and cannabis;
• Class C, including ketamine, temazepam, valium and anabolic steroids;
• Not classified, including poppers and glues, solvents, gas or aerosols.
• 'New' drugs, including mephedrone and BZP, GBL, Synthetic Cannabinoids, Khat and Salvia Divinorum.

In addition to reporting by Class, a number of other composite drug groups are reported. These composite groups, and the individual drugs that they include, are:

• Opiates, including heroin and the illicit / non-prescribed used of methadone;
• Stimulant drugs, including cocaine, crack, crystal meth, ecstasy, amphetamines and poppers;
• Psychedelics, including LSD, magic mushrooms and ketamine;
• Downers / tranquilisers, including temazepam and valium.

The groups include illicit drugs across the legal classifications and reflect the drugs' shared properties, effects and characteristics, providing an additional measure to the class-based categorisation. For example, stimulant drugs may be used interchangeably by the same people at similar times and in similar settings. Drugs not included in the composite groups such as cannabis, anabolic steroids and glues, solvents, gas or aerosols, are included separately in appropriate figures where sufficient data are available to do this.

In addition to the 16 drugs included in the 2008/9 and 2009/10 surveys and the 5 new drugs included in the SCJS 2010/11 (mephedrone, BZP, GBL, synthetic cannabinoids and khat), the new drug salvia divinorum was added to the SCJS 2012/13. In the SCJS 2012/13 questionnaire, respondents were asked whether they had taken any of five drugs from a group of new drugs (BZP, GBL, synthetic cannabinoids, khat or salvia divinorum) and separately whether they had taken the new drug mephedrone. These new drugs have been excluded from the overall analysis presented in the report (therefore all percentages exclude new drugs) and the trend analysis to ensure consistency with previous sweeps of the SCJS. Section 2.7 of the report specifically examines use of new drugs. It should be recognised that as these drugs were previously (or currently) legal, for respondents reporting use of them ever, this does not necessarily represent an illicit activity.

1.6 A note on reference periods

In the survey, respondents were asked about their history of drug use over three different time periods. These, with their respective strengths and limitations, are:

• Self-reported use ever: whether respondents had used specific drugs at some point in their lives, providing useful contextual information when, for example, examining general attitudes to drugs. However, this is not a useful indicator of current drug use or recent trends since it can include people who have used a drug once, perhaps a long time ago;
• Use in the last year: whether respondents had used specific drugs in the year prior to interview. This time frame is generally regarded as the most stable measure of current drug use, especially when analysing trends over time;^[7]
• Use in the last month: whether respondents had used specific drugs in the month prior to interview. This time frame provides the most up-to date information on usage. It is particularly focused on when considering drug dependency. However, since it is a relatively short time period it is more prone to variation, for example, it may miss people who use drugs regularly but who have not done so within the last month.

1.7 Comparing the SCJS 2012/13 with the CSEW 2012/13

Due to the fact that the Crime Survey for England and Wales (CSEW) 2012/13 self-completion questionnaire was asked of respondents aged between 16 and 59 years while the SCJS was asked of respondents of 16 years and over (i.e. including those aged 60 or over), care should be taken when comparing SCJS and CSEW data. In this report, where comparisons are made with the CSEW 2012/13, the SCJS 2012/13 data have been filtered to exclude those aged 60 years and over. With regards to the self-completion module on drugs, the methodology and time frame of the CSEW 2012/13 were largely similar to the SCJS 2012/13 although there were slight differences in the specific drugs that respondents were asked about.^[8] The prevalence figures for drug use in the last year and ever in England and Wales in section 2.2 of the report are based on the following drugs only: powder cocaine, crack cocaine, ecstasy, LSD, magic mushrooms, ketamine, heroin, methadone, amphetamines, methamphetamine, cannabis, tranquilisers, anabolic steroids, amyl nitrite and any other pills/powders/drugs smoked.

1.8 Structure of the report

The report proceeds as follows:

Chapter 2 focuses on prevalence of illicit drug use in Scotland exploring trends in self-reported drug use from the SCJS 2008/09 to the SCJS 2012/13 and in comparison to the CSEW 2012/13 and looking at self-reported drug use by drug composite group, legal classification and specific drug type. This chapter also examines variations in self-reported drug use by demographic, socio-economic and geographical factors. Lastly this chapter focuses on prevalence of being offered drugs and the prevalence of new drugs.

Chapter 3 focuses on the experiences of those who reported drug use. This chapter begins by examining self-reported drug use in the last year before going on to specifically focus on the experiences of adults over 16 who have used one or more illicit drugs in the last month looking at frequency of use; drug dependency; ease of obtaining drugs in the last month; and accessibility of drugs. This chapter will then examine experience of drug use in the last year with regards to specific drugs, polydrug use and joint use of alcohol and drugs. This chapter concludes by examining experience of drug use ever by specifically looking at the age at which drug was first used; the drug first used; and methods of taking drugs.

Annex 1 contains additional data tables showing the percentage of adults who reported taking illicit drugs in the last month, the last year and ever. The data are broken down by a range of demographic, experiential and area-related variables.

Annex 2 provides information on the methods employed in the SCJS 2012-13, focussing specifically on the self-completion questionnaire. This includes information on the questionnaire, disclosure of sensitive information, drugs classification, interview techniques, and the weighting used in the analysis of the results.

1.9 Conventions used in figures and tables

The following conventions are used in the figures and tables for this report, including the annexes.

Figures and tables

Each figure or table has a title (1), the data source (survey and year) (2), a base definition and the unweighted base figures (3), and the SPSS data file variable name (4)^[9]. For example:

(1) Figure 2.3: % of adults aged 16 or over reporting use of drugs by composite group

(2) SCJS 2012/13

(3) Base: Adults aged 16 or over (10,224)

(4) Variable Names: QEVE, Q12M, Q1M

Unweighted base

All SCJS percentages and rates presented in the figures and tables are based on weighted data (see Annex 2 for further details). However, an unweighted base is given below the figure, or in the table, which represents the number of respondents interviewed in the specified group. All unweighted bases are rounded to base 10. Percentages and rates where the unweighted base is less than 50 are excluded from the report.

Percentages

Row or column percentages may not add to 100 per cent due to rounding. Most figures / tables present cell percentages where the figures refer to the percentage of respondents that have the attribute being discussed. The complementary percentage to add to 100 per cent may not be shown. Respondents could refuse to answer any question they did not wish to answer. The majority of questions also had a 'don't know' option. Percentages are often not shown for these response categories.

A percentage may be quoted in the report text for a single category that is identifiable in the figures / tables only by summing two or more component percentages. In order to avoid rounding errors, the percentage has been recalculated for the single combined category and therefore may differ by one percentage point from the sum of the percentages derived from the figures / tables. Percentages in the figures in the main body of the report are displayed to one decimal place.