Correlational Problems and Fallacies. James H. Steiger. Introduction. In this module, we discuss some common problems and fallacies regarding correlation coefficients and their interpretation Interpreting a correlation Correlation and causality Perfect correlation and equivalence
James H. Steiger
Each of the above 4 data sets has the following summary statistics:
Each has a best fitting linear regression line of
If two groups with different means and/or covariances are combined, the resulting mixture can exhibit spurious correlations.
Example. (C.P.) Suppose the correlation between strength and mathematics performance is zero for 6th grade boys, and zero for 8th grade boys. Does this mean it will be zero in a combined group of 6th and 8th graders?