LAUSR

caution is necessary when translating categorical diagnostic criteria into dimensional measures: clinical diagnostic criteria of a disorder do not need to be unidimensional as they were developed for categorical diagnoses that characterize and identify (extreme) configurations. Approaches to the measurement of depression are one of the key examples for this. Andreassen et al. review available instruments at the start of their paper, which is an important step to provide a benchmark for improvement and not to re-invent the wheel. Sometimes this type of narrative needs to be strengthened by a systematic review of the existing instruments and their validation results. The development of an instrument is not finished with a single study, but rather sets of studies accumulate evidence for the psychometric validity of an instrument, and often only for specific purposes. Finding, analysing and aggregating psychometric results from these studies is therefore an important task. Frameworks such as the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) offer tools to consolidate knowledge about existing instruments. Additionally, to show that the BTAS is actually better at measuring individual differences and predicting relevant outcomes than other available instruments necessitates comparative studies, investigating incremental predictive validity in addition to (a) whether the instruments measure the same construct and if so, (b) whether one does this better than another one. Andreassen and colleagues present an instrument validation that evidences very good psychometric properties of the BTAS in a general population sample. Their study further provides several directions for future thinking and debate about the measurement of behavioural addictions.