Annex 2: Self-completion methodology
This section provides more detail about the self-completion section of the questionnaire for the SCJS 2014/15 specifically for the questions covering illicit drug use. Details are also included about the self-completion interview, the weighting used on the data and the classifications of illicit drugs used in this report. Further information about the design of the SCJS is contained in Scottish Crime and Justice Survey: Main Findings 2014/15 report and in the accompanying Technical Report.
The self-completion interview
Fieldwork for the SCJS 2014/15 was continuous and took place between the 1st of April 2014 and the 31st of May 2015. Interviews were conducted face-to-face in-home and were administered by specially trained professional interviewers working for TNS BMRB using Computer Assisted Personal Interviewing ( CAPI). The questionnaire is completed by respondents on the interviewer's tablet PC (Computer Assisted Self-completion Interviewing - CASI). This ensures confidentiality when answering sensitive questions or those on illicit behaviour. The respondent was asked to follow the instructions on the screen of the tablet PC and enter their answers using a special pen to tap the touch screen appropriately. In 2014/15 the conversion rate from the main survey to self-completion was 87%. 71% of them entered their answers directly in to the tablet PC themselves and 16% asked the interviewer to administer the questionnaire for them. Of those where the interviewer administered the self-completion, in five per cent of cases, the respondent completed the section themselves after the first few questions being administered by the interviewer.
The SCJS questionnaire consists of three elements:
- The main questionnaire consists of a set of core modules asked of the whole sample, including demographics; and a set of full and quarter-sample modules, containing questions on a variety of topics;
- A victim form which collects details about the incidents a respondent may have experienced during the reference period (the 12 months prior to interview). This victim form can be repeated up to five times; the number of victim forms completed depends on the number and nature of incidents a respondent has experienced in the 12 month reference period;
- A self-completion questionnaire covering sensitive issues. All respondents were asked to complete the self-completion questionnaire, but had the option to refuse this.
Respondents to the self-completion questionnaire on illicit drug use were first asked whether they had used any of the 18 specific drugs ever, whether they had used 'legal highs' and also whether they had taken the fictitious drug semeron. Those respondents who have taken drugs in the past are then asked if they have taken them in the last 12 months and, for those who have, whether they have taken them in the last month.
A series of follow-up questions are asked for the different groups, including:
- For those ever using drugs, which drug was the first ever taken; at what age they first took drugs, and what methods of drug taking they have ever tried;
- For those using drugs in the last 12 months, whether they have mixed these drugs, consumed alcohol at the same time as taking them, how they would describe their usage, and whether they have taken anything else in the last 12 months which they thought was a drug;
- For those taking drugs in the last month, which one they have taken most often, how difficult it is to get hold of, where they obtained it the last time they took it, and, in the last month, how many times they have used it, whether they felt dependant on it, tried to cut down and whether they managed to.
- Those who have ever used cannabis, cocaine, ecstasy, tranquiliser or amphetamines in the last year were asked how they would describe their use of these drugs in the last 12 months.
- In 2014/15 a question on the generic use of 'legal highs' was added for the first time. This asked respondents about "a range of substances that are described as 'legal highs', 'designer drugs', or 'new drugs'. By this we mean substances which you take to get a 'high' and are not illegal to purchase (but are not prescribed by a doctor)". Respondents were asked whether they had ever taken any powders, pills, herbal mixtures or crystals that are sold as 'legal highs', even if it was a long time ago. Respondents were also asked whether they had used such substances in the last year what the appearance/form of these substances was.
The questions about which drugs respondents have taken are asked in a loop ( i.e. have you ever taken?) rather than by selection from a single list of drugs.
Disclosure of sensitive information
Given the sensitive nature of the questions, especially as the majority of the questions on illicit drug use were on offending behaviours rather than victimisation (as opposed to the remainder of the self-completion questionnaire and the main questionnaire), a separate 'Don't wish to answer' button was provided at the top of the screen at every question in the self-completion section of the questionnaire.
At the start of the questions on illicit drug use, respondents were reminded that the answers they gave were completely confidential, reminded not to answer the questions including any drugs for which they had a prescription, and asked to answer the questions honestly: "The following questions ask whether or not you have ever used drugs. Please answer them honestly. The answers you give are completely confidential. Please DO NOT tell us about drugs you have been given on prescription."