2.2. Study Selection

Studies were included if they (1) involved participants who were aged 10–19 years at the first assessment time point, (2) applied at least one continuous measure for social anxiety and for a dimension of peer functioning, (3) measured the prospective associations between peer functioning and social anxiety, and (4) were published in English language, peer-reviewed, and indexed scientific journals. Studies were excluded if (5) they were primarily interested in studying individuals with neurodevelopmental conditions or physical health conditions. The reason is that findings from these studies may have limited generalisability to the general population. Studies were also excluded if (6) the same sample and measures were used in another study already identified in this review, or (7) the study was a review article, a conference abstract or paper, or a research dissertation.