基于概化理论和边际效用递减法则的测验长度研究

测验长度(test length)是影响语言测试信度和效度的重要因素之一。本文借助概化理论(Generalizability Theory,GT)的固定侧面s×(i:p)嵌套设计和边际效用递减法则(the Law of Diminishing Marginal Utility),对中国汉语水平考试(HSK[中级])的测验长度进行了实证研究。研究结果显示:由130题构成的HSK[中级]测验具有相当高的测验信度,概化系数(Eρ2)可达0.8890,即使将测验的题目数量减少至120题或110题,测验的概化系数仍可以达到0.8856和0.8816(分别降低了0.38%和0.83%),这种测验长度的缩减不仅明显地降低了研发成本,而且提高了测试效率,完全能够满足标准化考试在误差控制方面的较高要求,并确保测验结果和分数解释具有较高的信度和效度。

Test Length Study of the HSK[ Intermediate ] Based on Generalizability Theory and the Law of Diminishing Marginal Utility

Test length is always considered to play a crucial role in affecting the measurement error and reliability. This research, applying both Generalizability Theory and the Law of Diminishing Marginal Utility,investigated the appropriateness of item numbers in the revised edition of The Chinese Proficiency Test （ HSK [ Intermediate ] ）. First, it conducted a Generalizability study of HSK [ Intermediate ] with the design of items （i） nested within sections （p） and examinees （s） crossed with both s x （i ：p）. Variance components were estimated for the s, p, and i：p main effects, and for sp and si ：p interaction effects ; Secondly, this research carried out a Decision study （D study） with the section facet fixed for the design of S x （I： P） to obtain estimated error variance and reliability-like coefficients （generalizability and dependability coefficients）; Thirdly, it made a comprehensive evaluation of the reasonableness of item numbers for the fixed sections and total test of HSK [ Intermediate ] based on the D-study combined with the Law of Diminishing Marginal Utility. The research result indicated that the current test length of HSK [ Intermediate~ was desirable both from reliability and economic perspectives. The test will still reach a comparatively high reliability coefficient, even the item numbers were shortened from 130 to 120 or 110.