在問卷調查的訪員訓練中，訪員均被教導必須避免第三者在場的訪問情境。但是，歐美的研究發現，實際執行的訪問調查不見得能控制百分之百無第三者的在場。不同的研究對第三者在場是否影響訪問結果則尚無一致的結論。不過支持第三者在場對訪問結果有影響者居多，只是影響關係為何仍有待進一步瞭解。至於在台灣執行的訪問調查中，第三者在場效應的研究至今闕如。因此，本研究企圖比較不同類型問卷題目間是否有第三者在場的訪答效應，並分析此效應會以何種形式存在。本研究的分析資料來自台灣社會變遷基本調查計畫三期二次卷│（1996），並從兩個面向─答題品質與回答結果－探討訪答效應。初步的結果發現受訪者在事實性題目的答題品質比其他型題目者好。但進一步的邏輯迴歸分析結果則顯示第三者在場對各類型題目的答題品質並無明顯的影響。在回答結果的分析則顯示，社會贊許性題目多半無第三者在場訪答效應。可是第三者在場對回答結果的影響卻發生在事實性題目與敏感性題目上。雖然分析結果無法完全支持第三者在場對敏感性與社會讚許性題目具有訪答效應的理論假設，但也並未因此否決第三者在場訪答效應仍然存在的事實。未來，無論是在與第三者在場訪答效應有關之理論發展、研究開發，或實務工作上均有待繼續努力。

Interviewers are trained to conduct private interviews but would find that the presence of others in practice is hard to avoid. Despite of divergent conclusion, most of the previous studies support the importance of the third-person effect. This study examines the extent to which the presence of the third-person affects survey response across three types of questions concerning family, marriage and gender roles respectively Characterized by fact, sensitivity, and social desiribility attributes.The data analyzed is from Social Change Survey conducted in 1996. The quality of response to factual questions is found better than that to other types of questions. However, logistic regression analysis shows that the presence of the third-person does not affect the quality of response to three types of questions. On the other hand, the actual response to factual and sensitive questions varies with the presence of the third-person. The third-person effect does not happen to the response to the questions with social desirability.This study does not fully support the hypotheses that the third-person would affect the quality of response and actual response to sensitive and social desirable questions more than that to factual questions. However, it the findings does not totally reject the third-person effect. In conclusion, theoretical development and empirical studies on the third-person effect are needed in the future.