Abstract
INTRODUCTION: There is an obvious need for efficient measurement of neuropsychiatric phenomena. A proven method-computerized adaptive testing (CAT)-is not feasible for all tests, necessitating alternatives for increasing test efficiency. METHODS: We combined/compared two methods for abbreviating rapid tests using two tests unamenable to CAT (a Continuous Performance Test [CPT] and n-back test [NBACK]). N=9,498 (mean age 14.2 years; 52% female) were administered the tests, and abbreviation was accomplished using methods answering two questions: what happens to measurement error as items are removed, and what happens to correlations with validity criteria as items are removed. The first was investigated using quasi-CAT simulation, while the second was investigated using bootstrapped confidence intervals around full-form-short-form comparisons. RESULTS: Results for the two methods overlapped, suggesting that the CPT could be abbreviated to 57% of original and NBACK could be abbreviated to 87% of original with the max-acceptable loss of precision and min-acceptable relationships with validity criteria. CONCLUSIONS: This method combination shows promise for use in other test types, and the divergent results for the CPT/NBACK demonstrate the methods' abilities to detect when a test should not be shortened. The methods should be used in combination because they emphasize complementary measurement qualities: precision/validity..