Figure 1From: The use of cognitive ability measures as explanatory variables in regression analysisMeasurement error under IRT models: (a) for the simple model whose measurement error is expressed in equation (5); (b), (c), (d) for more typical 3PL tests of length 20, 40 and 80 items. (a) Measurement error for simple model, J=20, (b) Measurement error for typical 3PL, J=20, (c) Measurement error for typical 3PL, J=40, (d) Measurement error for typical 3PL, J=80.Back to article page