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. 2023 Jan 5;56(1):301–317. doi: 10.3758/s13428-022-02038-5

Fig. 5.

Fig. 5

Permutation analyses of the effect of task length and sample size on the reliability of accuracy-derived learning scores. a We varied the number of blocks (max 45) to be included in the reliability calculation. The top figure shows the Cronbach alpha, and its Feldt 95% CI for each task length. The dashed horizontal line indicates the .65 level. The bottom figure shows the width of the 95% CI only. Increasing task length increases the point estimate of reliability, but has only a minor effect on its precision. b We varied the number of subjects (max 180) to be included in the reliability calculation. The top figure shows the mean Cronbach alpha across 100 random samples of subjects, and its Feldt 95% CI, for each sample size tested. The dashed horizontal line indicates the .65 level. The bottom figure shows the width of the 95% CI only. Increasing sample size has no effect on the point estimate of reliability, but increases its precision. The same pattern is observed as in the analysis or RT-derived learning scores, reported in the main text, the only difference is the overall lower alpha values