台灣簡明版世界衛生組織生活品質問卷的信度概化研究

Abstract

信度是屬於測驗分數結果的一項特質，而不是屬於測驗工具本身(Gronlund & Linn, 1990)。因此每個研究都應該報告自己的研究樣本所估計出的信度係數。但實際上許多研究都沒有報告自己的信度係數。有鑑於此，Vacha-Haase於1998年提出一種信度的整合分析法，稱為信度概化法(reliability generalization, RG)，藉此整合使用同一個測量工具且有報告信度係數的許多研究。在台灣尚未有信度概化研究，因此本研究將針對台灣簡明版世界衛生組織生活品質問卷（台灣版WHOQOL-BREF）進行信度概化研究，同時也修正一些過去信度概化研究可能有的問題，目的是（一）討論題目、量尺等等各方面完全一樣的測量工具在不同研究中，不同群體的受試者產生的Cronbach's α有何變異。（二）這樣的變異可以用哪些和研究參與者有關的因素（例如：參與者性別、年齡）來預測。台灣版WHOQOL-BREF包含了生理、心理、社會關係和環境四個範疇。結果發現不管在整份問卷或四個範疇，Cronbach's α在不同研究的變異程度都不小，但大部分研究都有達到.7，一般認為可接受的信度數值。測驗分數的標準差對整份問卷和四個範疇的Cronbach's α都有顯著影響。若去除掉分數標準差的影響，平均年齡是最有影響的變項，平均年齡越大，生理範疇的Cronbach's α也會越大，但環境範疇的Cronbach's α會越小。

“Reliability refers to the results obtained with an evaluation instrument and not to the instrument itself” (Gronlund & Linn, 1990). Therefore, all researchers should provide reliability form the data actually analyzed in their study. However, in the past many researchers didn’t report it. Hence Vacha-Haase (1998) proposed the reliability generalization (RG) method which is a meta-analytic procedure for synthesizing reliability estimates from different studies. Because there hasn’t been any reliability generalization study in Taiwan, we conduct a reliability generalization study of the WHOQOL-BREF Taiwan version to explore the amount of variability in Cronbach's α across studies, and to examine the factors that may predict the variability in Cronbach's α. The WHOQOL-BREF Taiwan version encompasses four domains: physical health, psychological, social relationships and environment. The results revealed that Cronbach's α for the complete questionnaire and four domains across studies were fairly variable, but most of them were higher than .7, an acceptable value for a measurement. Cronbach's α were substantially related to standard deviations of scores. After removing the effect of standard deviations of scores, mean age was the primary predictor of Cronbach's α. Higher mean age was associated with higher Cronbach's α for physical health domain, but lower Cronbach's α for environment domain.