Table 4.

Detailed description of the additional assessment items.

Domain	Assessment Items
Coverage of training costs (self, other)	Single question developed by the researcher to assess the impact of cost coverage on the training effect (1 item).
Desire to improve social relationships	Single question developed by the researcher to assess the effects of the desire to strengthen social interactions on the training effect and to classify it as a confounder when there is a difference between the intervention and control groups. “Yes”, “sometimes”, and “no, I’m totally satisfied” are the response possibilities (1 item).
Expectations for the training programme	Assessed by a table where participants rate the effect they believe a training programme can have on the outcome parameters and the training aims.
Feeling of belonging to a group	Single question developed by the researcher to assess the impact of group identification on the training effect and to categorise it as a confounder when there is a difference between the intervention and control groups (1 item).
Frequency of application of trained content	Single question formulated by the researcher to evaluate the influence on the sustainability of the training effect. There are 6 response options representing increasing frequency (1 item).
Intention to complete the whole training programme	Single question developed by the researcher to assess the participants’ intention to complete the full training. “Yes”, “not sure yet”, “definitely not”, and “I have already attended other modules” are the response possibilities (1 item).
Medication	A single question is asked about the number of different medications that are taken.
Socio-demographic data	Age, gender, education, income, family status, relationship status, employment status, and earlier trainings (14 items).
Stressful life events within the last 3 months	Single question developed by the researcher to assess the impact of a stressful life experience that is still viewed as unpleasant on the training effect and to serve as a matching criterion (1 item).