Testing the draft questionnaire in a group of CST users

This section describes the aims of this part of the study; the recruitment of

participants, the inclusion and exclusion criteria, data collection and data handling, the chosen measurement model, the psychometric methods applied to the data, and analysis for assessing the measurement properties according to the FDA guidance.

4.10.1 Assessing the measurement properties

The aim of the sub-study was to field test the draft 52-item WHHQ with a group of CST users, evaluate its psychometric properties and reduce and refine the items.

4.10.2 Recruitment

CST users were recruited for this sub-study using the same methods reported above (pg. 100). CST practitioners registered to be involved via email and by return were allocated a practitioner ID (PID) and were sent a guide on how to administer the data collection. The guidance provided the aims and objectives of the study, the inclusion and exclusion criteria, the timelines for the study, how to administer the

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data collection, including how to allocate a client ID (CID), and what information to document. Guidance on how to add scores on a completed questionnaire was given and how to obtain more questionnaire booklets, if needed. Questionnaire booklets and prepaid envelopes were sent by post to registered practitioners. Recruitment posters were displayed within practitioner clinics and CST users were invited to complete a questionnaire before a session of CST.

4.10.3 Inclusion and exclusion criteria of CSTA participants

Any new or existing clients of participating CSTA member practitioners were eligible for this study. CST users under the age of 16, those having multiple treatment modalities during their sessions e.g. psychotherapy and CST or acupuncture and CST, those who may be traumatised and unable to undertake the task at hand and anyone about whom practitioners had doubts, for whatever reason, were excluded.

4.10.4 Data collection and method of administration

The draft instrument (52-item WHHQ) was self-administered by CST users whilst waiting for their CST session or as part of their therapy session depending on the facilities and/or preference of each study practitioner. Participants were deemed to have consented by returning a completed questionnaire.

4.10.5 Data handling and cleaning

Completed questionnaires were returned by post to the researcher. On receipt questionnaires were checked to ensure they had correct PIDs and CIDs to enable tracking. Data were put into the statistical software package SPSS (IBM, version 22). To ensure confidentiality, the data protection act (1998) was adhered to. Data were stored as described in the data storage section (pg.112).

4.10.6 Scoring rules and missing data for WHHQ and comparator measures

To meet the design requirements of the COSMIN checklist considerations for scoring rules and for missing data were determined prior to data collection. Here all measures (including 52-item WHHQ and 25-item WHHQ, HEHIQ, SF-12v2 and

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WEMWBS) and the way they had been scored and missing data handled are described.

WHHQ: Items were scored as indicated on the draft instrument, with each option given a rating from 0 to 4.

25-item WHHQ: A total score is calculated by adding the 25 individual statement scores. The minimum score is 0 and the maximum score is 100 with high scores implying higher levels of wellbeing.

Each questionnaire was scored according to the questionnaire instructions: SF-12v2: Calculated as reported in the handbook (Ware et al., 2010). The physical component summary score yields a single score that can be used as an overall measure of physical health and the mental component summary an overall assessment of mental health. Scores of less than 40 indicate impaired functioning or wellbeing associated in the domain. The scores of each domain are not

combined, the SF12v2 does not have a total score (Ware et al., 1995).

WEMWBS: Items were added to create a total score between 14 and 70. Higher scores indicate higher levels of mental wellbeing.

HEHIQ: Each of the five subscales has a score and these are added to create a total score. Scores can range between 20 and 100, higher scores indicate more positive state of health.

Missing items were handled in the following manner: for each instrument, scores were mean imputed if the number of missing items on the instruments for a

respondent was three or fewer, excluding demographic data and anchor questions; i.e. the mean score of the reported items was assigned to each of the missing items for that person. Scores were rounded to the nearest whole number.

According to Streiner and Norman (2008), if the number of omitted items is small (less than 5%), then assigning the mean score probably will not distort the results too much. In the case of WHHQ, 5% of 52 items is 2.6 items rounding up to 3.

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If the number of missing items for a respondent was greater than three for any particular questionnaire, the total score was deemed to be missing and the respondent’s data were removed from the dataset of that comparator measure. Imputed datasets were analysed and reported, noting the number of frequencies of missing data per item. If a respondent gave two answers for an item or endorsed a point between two options, the mid-point between the two scores was inputted. For example: for a respondent endorsing both 3 and 4 for an item; 3.5 was inputted.

4.10.7 Floor and ceiling effects

Measures of central tendencies were determined and the standard deviation was calculated for each item. Histograms were created to provide a visual

representation of the distribution. Items were analysed to identify any floor and ceiling effects at scale level and at item level to see if all response options were being used. No floor effects or ceiling effects were identified.