Maternity care survey 2018: technical report

7. Analysis and Reporting

The survey data collected and coded by Quality Health Ltd were securely transferred to the Scottish Government, where the information was analysed using the statistical software package SAS Enterprise Guide version 7.1.

Number of Responses Analysed

The number of responses that have been analysed for each question is often lower than the total number of survey responses received. This is because not all of the questionnaires that were returned could be included in the calculation of results for every individual question. In each case this was for one of the following reasons:

• The specific question did not apply to the respondent and so they did not answer it. For example if they had a home birth and therefore did not answer questions about their experience of care in hospital after the birth.
• The respondent did not answer the question for another reason (e.g. refused).  People were advised that if they did not want to answer a specific question they should leave it blank.
• The respondent answered that they did not know or could not remember the answer to a particular question.
• Responses may be removed following validation checks, for example if a respondent selected an invalid combination of responses. Improved validation checks were introduced for this survey to ensure consistency between online and paper responses. 

The number of responses that have been analysed nationally for each of the positive / negative questions are shown in Annex A.

Weighting

When conducting a survey, it is important to have a representative sample of the population you are interested in. Applying weighting methods reduces potential bias by making the results more representative of the population.

Survey weights are numbers associated with the responses that specify the influence the various observations should have in the analysis. The final survey weight associated with a particular response can be thought of as a measure of the number of population units represented by that response.

Results at all levels of reporting are weighted. A review of the weighting methodology was undertaken in advance of the 2018 survey, leading to some changes in the weights applied. Full details of the review and the methodology applied for the 2018 survey are available in the Weighting Review Paper which can be found at www2.gov.scot/Resource/0054/00545079.pdf.

Backdating of Previous Surveys

Due to the change to the weighting methodology applied to this survey, figures from the 2013 and 2015 survey have been backdated where appropriate to ensure comparisons over time are available. Reports specifically relating to the 2013 and 2015 surveys will not be updated to include the backdated figures.

As part of the backdating process, the improved validation checks applied to the 2018 survey have been applied to the 2013 and 2015 survey responses. The total number of responses for analysis may therefore differ to those previously published. 

Percentage Positive and Negative

Per cent or percentage positive is frequently used in reporting results from this survey. This means the percentage of people who answered in a positive way. Annex A details which answers have been classed as positive and negative for each question.

Percentage positive is mainly used to allow easier comparison, particularly where responses are on a scale where there may be multiple responses being classed as positive or negative. There is also a belief that differences between answers on scales with five or more points may be subjective.  For example there may be little or no difference between a person who “strongly agrees” and one who “agrees” with a statement. In fact some people may never strongly agree or strongly disagree with any statements.

As described in Section 3 of this report, these results are based on a sample of patients and are therefore affected by sampling error. The effect of this sampling error is relatively small for the national estimates. However, when comparisons have been made in the analysis of the survey results, the effects of sampling error have been taken into account by the use of confidence intervals and tests for statistical significance. Only differences that are statistically significant are reported as differences within the analysis. All significance testing is carried out at the 5% level.

Quality Assurance of the National Report

A small group of Scottish Government analysts were sent a draft version of the national report for quality assurance. Feedback included suggestions on ways in which to report data as well as comments about the context for the survey. These were taken into account in finalising the national report. 

Revisions to previous publications

A copy of our revisions policy is available at: www.gov.scot/Resource/0052/00522934.pdf