過去的實證研究已經一再地指出，偏差友伴與個人偏差行為間具有強的關連性。但，當今社會學和犯罪學領域的研究中，卻有兩個相互競爭的觀點嘗試解釋兩者間的關連。一為「影響性效果」，此觀點認為偏差友伴確實地影響著個人的偏差行為發展；另一個觀點為「選擇性效果」，主張個人會選擇跟自己相似的人結交朋友，或個人會「投射」認為朋友的行為應跟自己是相似的，基於此觀點，偏差友伴與個人偏差行為的高相關性只不過是「自我選擇」下的產物。本研究使用2,280 位來自於「台灣青少年計畫」的台灣青少年樣本，並配上以班級為單位的友誼網絡資料，用以檢測偏差友伴和個人偏差行為間的實際連結。為了排除「選擇性」及「投射性」的偏誤，本文除了使用貫時性資料外，並且使用兩種不同偏差友伴的測量方法，一為傳統的自陳式測量，另一種為社會網絡測量的技術。分析結果顯示，縱使「選擇性」、「投射性」和「樣本流失性」的偏誤排除後，偏差友伴和個人偏差行為間仍具有實際的關連性。另外，本文進一步發現，自陳式測量相較於社會網絡測量法，更有可能高估偏差友伴對偏差行為的解釋力。根據分析之結果，本研究建議，當使用自陳式測量的偏差友伴預測個人偏差行為時，應同時在分析模型中考慮「自我控制」和「父母監控行為」對個人偏差行為的效果，用以減低自陳式測量所造成的「投射性」偏誤。

Consistently, empirical findings have indicated that the presence of deviant peers is one of the strongest predictors of adolescent delinquency. While this association is widely accepted, the mechanisms at work have been disputed. Two competing approaches, the influence and selection approaches, have received the most scholarly attention. The influence model argues that an association with deviant peers has a real and causal impact on adolescent delinquency. Conversely, the selection model posits that perceived associations are the result of homophily, as people tend to form or select friendships with others who share similar characteristics. Using a sample of 2,280 Taiwanese adolescents from the Taiwan Youth Project along with friendship network data, this study reexamines the association between deviant peers and delinquency. In order to rule out potential biases, this study uses both perceptual and direct measures of deviant peers. The perceptual measure of deviant peers refers to an individual's report of his or her friends' delinquent behavior, whereas the direct measure is formed through an analysis of the friendship network data. Controlling for selection and projection effects, the results show that the effect of deviant peers on delinquency remains significant. The results also indicate that using a self-report measure of deviant peers, in contrast to a social network analysis, potentially overestimates the deviant peers-delinquency relationship. Finally, this study's results support the combined use of both self-report measures of deviant peers in conjunction with self-control and parental monitoring measures to best account for the influence of deviant friendships on delinquency.