內部一致性 20120131更新

Internal consistency reveals the correlation or consistency of the items in the same domain in a questionnaire. It is often revealed by Cronbach's α.

中文解釋：
內部一致性是指問卷中同一面向的題目之間的相關性或一致性，通常以Cronbach's α表示。

判斷標準：Cronbach's α 介於0.7-0.9為內部一致性良好，α>0.95可能表示有些題目概念重複，可考慮刪除。 

臨床意義：
內部一致性越高，表示問卷各題所測量的概念之相關性越高。

限制：
Cronbach's α的數值易受問卷的題數影響。題數越多，Cronbach's α值越大。

研究設計：
邀請問卷之適用對象填寫問卷，再依據填寫結果計算問卷每個面向的Cronbach's α。

參考資料：

Cronbach, Lee. (1951). Coefficient alpha and the internal structure of tests. Psychometrika, 16, 297-334.

Rush, A. J., Trivedi, M. H., Ibrahim, H. M., Carmody, T. J., Arnow, B., Klein, D. N., . . . Keller, M. B. (2003). The 16-Item Quick Inventory of Depressive Symptomatology (QIDS), clinician rating (QIDS-C), and self-report (QIDS-SR): a psychometric evaluation in patients with chronic major depression. Biological Psychiatry, 54, 573-583.

Terwee, C. B., Bot, S. D. M., de Boer, M. R., van der Windt, Dawm, Knol, D. L., Dekker, J., . . . de Vet, H. C. W. (2007). Quality criteria were proposed for measurement properties of health status questionnaires. Journal of Clinical Epidemiology, 60, 34-42.