# Different results with repeated measure correlation (rmcorr) and cor.test

I did a repeated measure correlation (package: rmcorr) inculding two data points. But if I look also at the correlation separately for each point, I´m a little bit confused because the repeated measure correlation gave me a positive correlation and the separate correlations gave me at each point a negative correlation (see results below). Is this result only explainable through the violation of independence? Thank you for answering my question.

Kind regards,

Daniel Groß

Repeated measures correlation

r 0.2760491 degrees of freedom 43 p-value 0.06642702 95% confidence interval -0.0264911 0.5322632

T1 (cor.test) Pearson's product-moment correlation

t = -1.1941, df = 42, p-value = 0.2391 alternative hypothesis: true correlation is not equal to 0 95 percent confidence interval: -0.4536775 0.1222541 sample estimates: cor -0.181203

T2 (cor.test) Pearson's product-moment correlation

t = -4.1108, df = 42, p-value = 0.0001791 alternative hypothesis: true correlation is not equal to 0 95 percent confidence interval: -0.7182965 -0.2839074 sample estimates: cor -0.5356405

• Note that for both the rm and t1 correlations that the confidence interval includes 0, so the evidence that these correlations are either positive or negative is weak. Commented Jul 19, 2017 at 9:31
• It is perfectly possible but I am not sure what you mean by lack of independence. Commented Jul 19, 2017 at 10:49