Another cautionary note is in order with regard to neuropsychological processes or brain structures in which there has been a failure to detect alcoholism-related relationships. That is, although negative results from research studies may be due to genuinely preserved abilities and brain tissue, it is possible that the data sets lack the statistical power needed to detect bona fide differences between populations. Accordingly, studies that have examined certain functions and structures but have not found alcoholism-related abnormalities cannot characterize confidently the functions or regions as spared, because the results may have been obtained from inadequate sample sizes or because the variability within the measures was too large. In many of those studies, the probability that real associations exist but were not detected (Type II error) might be high but not reported. Thus, conclusions regarding spared functions cannot always be drawn with adequate certainty from the current literature. In any case, the identification of preserved functions — whether they are spared, compensatory, or recovered — is of great benefit to the scientific and healthcare communities. Once intact functions are identified, clinicians
