RT Journal Article
T1 Non-normal Data in Repeated Measures ANOVA: Impact on Type I Error and Power.
A1 Blanca-Mena, María José
A1 Arnau, Jaume
A1 García-Castro, F. Javier
A1 Alarcón-Postigo, Rafael
A1 Bono Cabré, Roser
K1 Psicología - Investigación
AB Background: Repeated measures designs are commonly used in health and social sciences research. Although there are other, more advanced, statistical analyses, the F-statistic of repeated measures analysis of variance (RM-ANOVA) remains the most widely used procedure for analyzing differences in means. The impact of the violation of normality has been extensively studied for between-subjects ANOVA, but this is not the case for RM-ANOVA. Therefore, studies that extensively and systematically analyze the robustness of RM-ANOVA under the violation of normality are needed. This paper reports the results of two simulation studies aimed at analyzing the Type I error and power of RM-ANOVA when the normality assumption is violated but sphericity is fulfilled. Method: Study 1 considered 20 distributions, both known and unknown, and we manipulated the number of repeated measures (3, 4, 6, and 8) and sample size (from 10 to 300). Study 2 involved unequal distributions in each repeated measure. The distributions analyzed represent slight, moderate, and severe deviation from normality. Results: Overall, the results show that the Type I error and power of the F-statistic are not altered by the violation of normality. Conclusions: RM-ANOVA is generally robust to non-normality when the sphericity assumption is met.
PB Grupo Editorial de Psicofundación
YR 2022
FD 2022-09-25
LK https://hdl.handle.net/10630/28160
UL https://hdl.handle.net/10630/28160
LA eng
NO Blanca, M. J., Arnau, J., García-Castro, F. J., Alarcón, R., & Bono, R. (2023). Non-normal data in repeated measures ANOVA: Impact on Type I error and power. Psicothema, 35(1), 21-29. https://doi.org/10.7334/psicothema2022.292
NO This research was supported by grant PID2020-113191GB-I00 from the MCIN/AEI/ 10.13039/501100011033.
DS RIUMA. Repositorio Institucional de la Universidad de Málaga
RD 21 ene 2026