Retest reliability of the Halstead Impairment Index in a normal, a schizophrenic, and two samples of organic patients.

In a 1974 study Matarazzo, et al. reported the test-retest reliability of the Halstead-Reitan Neuropsychological Battery for a sample of normal young men and a comparison group of older Ss with cerebrovascular disease. The present study extended this earlier one by addition of comparable test-retest findings from two additional comparison groups: a sample of chronic schizophrenic Ss and a sample of organic patients who underwent endarterectomy. Despite the lack of comparability across the four samples on many dimensions, including age and test-retest interval, the results again reveal a high degree of clinical as well as purely psychometric reliability for most of the tests in the neuropsychological battery and the additional suggestion for further research that the test-retest instability found for some of the Ss in the schizophrenic sample may, itself, hold promise of differential clinical significance in the diagnosis of a "schizophrenic" vs. "organic" process.