Item difficulty analysis of the tactual performance test trials.

A study of item difficulty was performed on data from the Tactual Performance Test trials (preferred, nonpreferred, and both hands) on three groups (normal, alcoholic, and heterogeneous). The total sample size was 314. The three-way split-plot analysis of variance yielded three significant two-way interactions, i.e., group by trial, group by block, and trial by block, thereby making the interpretation complex. One finding is that the blocks at the top of the board are more difficult than the blocks at the bottom of the board.