Figure 3
Optimized stimulus lists. (Top left) Test information functions for the three stimulus lists. The curves are overlapping over the full range, predicting near identical performance on each list irrespective of individual ability. The x-axis shows ability estimates based on the Rasch model. The upper x-axis shows the estimated WJ-Word-ID raw score equivalent based on the linear relationship between ability estimates and WJ-Word-ID scores. The pink lines indicated grade level equivalents for WJ-Word-ID scores (based on the WJ manual). Test information is high for participants scoring above the 1st grade level on the WJ-Word-ID. (Top right) Scatter plots of ability estimates based on each list. Test–retest reliability for each individual list is greater than r = 0.92. (Bottom panel) Correlations between ability estimates on each list and WJ-Word-ID scores. The blue–gray–red colormap indicates standard scores as in Fig. 2. Even a single short list provides an accurate and reliable estimate of WJ-Word-ID ability.
