複本信度 (Alternate-Forms Reliability)

Alternate-Forms Reliability “a form of reliability in which alternate forms of the same test are given to a group of heterogeneous and representative subjects; scores for the two forms are then correlated.”

中文解釋:複本信度是指編制一份量表，稱為正本，然後編制另一份性質、內容、難度均相同、但文字不同的題目，作為複本，並以正本與複本針對相同對象實施測量，求得兩份測量結果，計算其相關程度，了解測量工具的信度。

臨床意義:如驗證後正本與複本得到結果有高度一致性，則可運用於臨床上避免再測時個案產生學習或練習效應，以減少評估誤差。

判斷標準:計算相關係數 (如: Pearson’s r)。相關係數介於0.25-0.5為尚可 (fair)，介於0.5-0.75為中度至良好(moderate to good) ，大於0.75為良好至極佳(good to excellent) 。

Reference:
Stigler, Stephen M. Francis Galton's Account of the Invention of Correlation. Statistical Science, 1989, 4,73–79.
Benedict RH, Zgaljardic DJ. Practice effects during repeated administrations of memory tests with and without alternate forms. Journal of Clinical Experimental Neuropsychology. 1998, 20, 339-352.

研究設計:受試者在同一個時間點，接受兩份測驗(一份為正本，另一份為複本) 。

參考文獻:

Schmidt KS, Mattis PJ, Adams J, Nestor P. Alternate-form reliability of Dementia Rating Scale-2. Archives of Clinical Neuropsychology, 2005, 20, 435-441.