Measurement instruments

Social participation is measured with the PsyMate experience sampling device. This form of Experience Sampling Measurement (ESM) has high ecological validity [17]. ESM is a self-assessment technique using random time sampling, and has the advantage that it can assess mental state and social context in everyday life as it occurs. Because the ESM assesses ‘at the moment’ it is less vulnerable for recall bias and a valuable instrument to assess clinical phenomena in the real world [18]. ESM is effective for patients with a psychotic disorder with current symptoms, as well as for patients with a psychotic disorder in remission [19]. A review of studies using the ESM shows it to be valid for measuring situational characteristics, such as social environment [20]. Event stress, social environment and company (time spent in company with others and the kind of company) are operationalized in accordance with the work of Collip et al. [19]. Research on the (social) context of delusions in schizophrenia shows the ESM to be a valid aid in collecting data of daily life social situations [21]. Momentary paranoia, using four established ESM items, is a valid state measure to assess paranoia [22]. Perceived social threat, using four established ESM items, is a valid measure to assess perceived social threat as a more subtle indicator of paranoia [19]. An overview of measurement objectives can be found in Table​Table11.

Measurement objectives

GPTS Green et al. Paranoid Thought Scales, SIAS Social Interaction Anxiety Scale, BDI-II Beck Depression Inventory, ISMI Internalized Stigma of Mental Illness, BCSS Brief Core Schema Scales, SBQ Safety Behavior Questionnaire – persecutory delusions, DACOBS Davos Assessment of Cognitive Biases Scale, SOFAS Social and Occupational Functioning Assessment Scale, MANSA Manchester Short Assessment of quality of life, TiC-P Trimbos/iMTA questionnaire for Costs associated with Psychiatric illness, SSQ Simulator Sickness Questionnaire, IPQ Igroup Presence Questionnaire, BARS Brief Adherence Rating Scale