CTTITEM: SAS macro and SPSS syntax for classical item analysis.
This article describes the functions of a SAS macro and an SPSS syntax that produce common statistics for conventional item analysis including Cronbach's alpha, item difficulty index (p-value or item mean), and item discrimination indices (D-index, point biserial and biserial correlations for dichotomous items and item-total correlation for polytomous items). These programs represent an improvement over the existing SAS and SPSS item analysis routines in terms of completeness and user-friendliness. To promote routine evaluations of item qualities in instrument development of any scale, the programs are available at no charge for interested users. The program codes along with a brief user's manual that contains instructions and examples are downloadable from suen.ed.psu.edu/-pwlei/plei.htm.
Lei
Pui-Wa
PW
Pennsylvania State University, University Park, Pennsylvania 16802, USA. puiwa@psu.edu
Wu
Qiong
Q
D006801:Humans; D008037:Linguistics / Q000379:methods* / Q000706:statistics & numerical data*