Inclusion or Exclusion?

Statistical procedures for performing profile analysis based on intra-individual comparisons of subtest scores are widely used by school psychologists everywhere. Despite the popularity of these procedures, examiners are often concerned that valid relative strengths or weaknesses will be missed in cases in which markedly discrepant scores skew the mean, which is used as the benchmark for all comparisons. Two alternate methods of analysis including or excluding the subtest in question have traditionally been proposed. Analysis of the formulas used in the different methods and a case example using WISC subtest scores are provided to demonstrate the counter-intuitive finding, first articulated by Silverstein (1984a,b), that both methods produce the same result.