Table 2.

Rules of thumb for addressing practice effects in clinical trials

Approach	Advantages	Pitfalls
Use of a control group	Necessary in placebo-controlled randomized clinical trial	Prone to confounding a practice effect with a treatment effect
Massed practice (multiple prebaseline testing)	Repeated testing during a prebaseline period may result in a task familiarity–based asymptote and can reduce interindividual and intraindividual variance due to subjects not fully understanding task demands.	Differential asymptotes between tests; possible ceiling effects; occlusion of treatment effects
Reliable change index	Is rigorous	Applicable to cases, not group means
Alternate forms	Clearly reduce practice effects	Forms may not be equivalent in difficulty level; influence of strategy formation
Practice-insensitive tests	Interpretation of improvement or lack of decline is straightforward	Relevance of cognitive operations; sensitivity to treatment