Lowered cutoffs to reduce false positives on the Word Memory Test

To adjust the decision criterion for the Word Memory Test (WMT, Green, 2003) to minimize the frequency of false positives.

Archival data were combined into a database (n = 3,210) to examine the best cut score for the WMT. We compared results based on the original scoring rules and those based on adjusted scoring rules using a criterion based on 16 performance validity tests (PVTs) exclusive of the WMT. Cutoffs based on peer-reviewed publications and test manuals were used. The resulting PVT composite was considered the best estimate of validity status. We focused on a specificity of .90 with a false-positive rate of less than .10 across multiple samples.

Each examinee was administered the WMT, as well as on average 5.5 (SD = 2.5) other PVTs. Based on the original scoring rules of the WMT, 31.8% of examinees failed. Using a single failure on the criterion PVT (C-PVT), the base rate of failure was 45.9%. When requiring two or more failures on the C-PVT, the failure rate dropped to 22.8%. Applying a contingency analysis (i.e., X²) to the two failures model on the C-PVT measure and using the original rules for the WMT resulted in only 65.3% agreement. However, using our adjusted rules for the WMT, which consisted of relying on only the IR and DR WMT subtest scores with a cutoff of 77.5%, agreement between the adjusted and the C-PVT criterion equaled 80.8%, for an improvement of 12.1% identified. The adjustmeny resulted in a 49.2% reduction in false positives while preserving a sensitivity of 53.6%. The specificity for the new rules was 88.8%, for a false positive rate of 11.2%.

Results supported lowering of the cut score for correct responding from 82.5% to 77.5% correct. We also recommend discontinuing the use of the Consistency subtest score in the determination of WMT failure.