They found that clique members compared with isolated children showed , on average , an increase in externalizing problems across that same period .
Through this study , Witvliet , van Lier , Brendgen , Koot , and Vitaro noted that externalizing problems increased among clique members .
clique members found that clique members compared with isolated children showed , on average , an increase in externalizing problems across that same period .
Through this study , Witvliet , van Lier , Brendgen , Koot , and Vitaro noted that externalizing problems increased among clique members .