Measuring access to social capital: the validity and reliability of the Resource Generator-UK and its association with common mental disorder.

Resource generators measure an individual's access to social resources within their social network. They can facilitate the analysis of how access to these resources may assist recovery from illness. As these instruments are culture and context dependent different versions need to be validated for different populations. Further, they are yet to be subjected to a thorough content validation and their reliability and validity have not been established beyond an examination of their internal scales. This paper reports the validity and reliability of a version suitable for general population use in the UK. Firstly, a qualitative process of item selection and review through focus groups and an expert panel ensured that the resource items were relevant. Also, cognitive interviews identified any significant problems prior to extensive piloting. Then we examined its internal domains using Mokken scaling in a small general population survey (n=295). Its concurrent validity with a similar instrument was tested in a further pilot (n=335) and these findings were supported by a known-group validity study (n=65). Its reliability was established in a test-retest study (n=47) in addition to an examination of the reliability coefficients of the internal scales. We found that the Resource Generator-UK has good psychometric properties, though there is some variation in performance between items and scales. Further, we found an inverse relationship with common mental disorder in the second pilot we undertook.