Assessment effects in educational and psychosocial intervention trials: an important but often-overlooked problem.
Baseline assessments and repeated measures are an essential part of educational and psychosocial intervention trials, but merely measuring an outcome of interest can modify that outcome, either by the measurement process alone or by interacting with the intervention to strengthen or weaken the intervention effects. Assessment effects can result in biased estimates of intervention effects and may not be controlled by the usual two-group randomized controlled trial design. In this paper, we review the concept of assessment effects and other related phenomena, briefly describe study designs that estimate assessment effects separately from intervention effects and discuss their strengths and limitations, review evidence regarding the strength of assessment effects in intervention trials targeting behavior change, and discuss implications for intervention research.
Associate Professor and Beerstecher and Blackwell Term Distinguished Scholar, School of Nursing, University of North Carolina at Chapel Hill, 7460 Carrington Hall, Chapel Hill, NC, 27599.
Mi-Kyung
MK
Song
Helen Denne Schulte Professor Emerita, School of Nursing, University of Wisconsin-Madison, Madison, WI.
Sandra E
SE
Ward
D018849:Controlled Clinical Trials as Topic / Q000379:methods; D003627:Data Interpretation, Statistical; D015438:Health Behavior; D006801:Humans; D010353:Patient Education as Topic / Q000379:methods*; D016032:Randomized Controlled Trials as Topic / Q000379:methods; D012107:Research Design; D040242:Risk Reduction Behavior
assessment effects; behavior change; bias; external validity; internal validity; interventions; measurement; randomized trials