Is calculating item discriminating value through t-test the only method? Are there other methods? Most importantly, in personality scales, while eliminating items, should one consider the only item discriminating value?
Item discrimination value is relevant for scale construction. An alternative to t-value is item-total correlation: generally, items with item total correlation more than .4 have significant t-discrimination value. But these days discrimination values are used as just screening criteria for further EFA and CFA where loading of items mainly decide whether items will be retained in final scale or not. Hope that helps, SS
The world of scale construction has more to offer then just EFA or CFA, You might want to learn about IRT models (Rasch, Graded Response, Mokken etc.). EFA and CFA are not really appropriate when you want to analyze categorical Likert Ordered Items. In IRT models one also uses item-rest total correlations, but one needs to know what one wants and does.
Thank you, Sanjay and Peter.
Peter, Can you link some researchers regarding IRT.
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