Repeated Measures Correlation

Bakdash, J. Z., & Marusich, L. R. (2017). Repeated measures correlation. Frontiers in psychology, 8(456), 1-13. doi: https://doi.org/10.3389/fpsyg.2017.00456

32 Pages Posted: 3 Sep 2016 Last revised: 26 Jan 2021

See all articles by Jonathan Bakdash

Jonathan Bakdash

U.S. Army Combat Capabilities Development Command Army Research Laboratory South at UT Dallas; Texas A&M University (TAMU), Commerce

Laura Marusich

US Army Research Laboratory

Date Written: December 20, 2016

Abstract

Repeated measures correlation (rmcorr) is a statistical technique for determining the common within-individual association for paired measures assessed on two or more occasions for multiple individuals. Simple regression/correlation is often applied to non-independent observations or aggregated data; this may produce biased, specious results due to violation of independence and/or differing patterns between-participants versus within-participants. Unlike simple regression/correlation, rmcorr does not violate the assumption of independence of observations. Also, rmcorr tends to have much greater statistical power because neither averaging nor aggregation is necessary for an intra-individual research question. Rmcorr estimates the common regression slope, the association shared among individuals. To make rmcorr accessible, we provide background information for its assumptions and equations, visualization, power, and tradeoffs with rmcorr compared to multilevel modeling. We introduce the R package (rmcorr) and demonstrate its use for inferential statistics and visualization with two example datasets. The examples are used to illustrate research questions at different levels of analysis, intra-individual and inter-individual. Rmcorr is well-suited for research questions regarding the common linear association in paired repeated measures data. All results are fully reproducible.

Keywords: correlation, regression, repeated measures, power, individual differences

JEL Classification: C12, C18, C30, C88

Suggested Citation

Bakdash, Jonathan and Marusich, Laura, Repeated Measures Correlation (December 20, 2016). Bakdash, J. Z., & Marusich, L. R. (2017). Repeated measures correlation. Frontiers in psychology, 8(456), 1-13. doi: https://doi.org/10.3389/fpsyg.2017.00456, Available at SSRN: https://ssrn.com/abstract=2833824 or http://dx.doi.org/10.2139/ssrn.2833824

Jonathan Bakdash (Contact Author)

U.S. Army Combat Capabilities Development Command Army Research Laboratory South at UT Dallas ( email )

Texas A&M University (TAMU), Commerce ( email )

2600 South Neal Street
Commerce, TX 75428
United States

Laura Marusich

US Army Research Laboratory ( email )

ATTN: RDRL-HRS-E
459 Mulberry Point Road
Aberdeen Proving Ground, MD 21005-5425
United States

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