摘要

本文為一研究方法上的探討，旨在了解由Roper機構於1959年起發展出的「相對可信度」題目，是否能有效測量出媒介的可信度、它會不會對某種媒介造成有利或不利的偏差。Roper式的「相對可信度」題目是這樣問的：「假如廣播、電視、雜誌和報紙在同一事件上報導有所差異，通常您會比較相信那一種媒介的報導？」）這種問法的效度如何，即使在國外，也並未經深入研究，而在台灣地區，這個領域更是一片荒蕪。

由於１）國外文獻的發現；２）本研究實的數據顯示，廣播及雜誌兩種媒介的可信度遠低於電視及報紙，故此本文在實際分析時，僅以電視及報紙作比較。

在方法上，本文運用媒介正確性、公正性、信任度、整体可信度及媒介選擇五個媒介可信度的不同層面，來印證Roper式的相對可信度題目，觀察在相對可信度題目選擇不同媒介的民眾（即電視相信者及報紙相信者），在其他五個媒介可信度題目的反應。

結果顯示，電視相信者在其他五個可信度題目上的反應相當一致，不論是那個題目，他們均給予電視較高的評價；反之，報紙相信者卻並不認為報紙比電視來得正確、來得公正，或更為信任報紙所報導的新聞。

這個現象似乎顯示Roper式的相對可信度題目，在以台灣地區的成人為樣本時，可能產生對報紙有利的偏差：因為報紙相信者比較禁不起「考驗」，當用其他不同的媒介可信度題目來作印證時，他們中的一部分，會改變其支持報紙的立場。或許他們原來的態度是没有如此傾向於支持報紙的，只是由於「相對可信度」題目的誤導，使他們選擇了報紙而已。

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二 中文部分
1. 鄭瑞城、曠湘霞。台灣地區成人收看電視的動機與行為研究，國立政治大學新聞研究所，民７２。
2. 賴光臨等。政令宣導與媒體效用之調查研究，國立政治大學新聞學系，民７３。