A comparison of the reliabilities of four types of difference scores for five cognitive assessment batteries

In recent years, studies have been conducted comparing the reliability of simple difference scores to differences computed via reliable component analysis (RCA). For the five cognitive assessment batteries examined here, RCA difference scores have been superior to simple difference scores in this regard. In the present study, the five cognitive assessment batteries are considered again, including a comparison of two alternative methods of difference score construction, the residualized and base-free difference methods, in order to determine if RCA outperforms the other methods as well. Results indicated that the RCA difference scores were more reliable in 68/70 comparisons between the four methods. When difference scores are a central part of test interpretation, clinicians should use the RCA scoring method because of the high reliability of the difference scores.