Your teacher asks you to generate a correlation between three variables: dstat (disease), wt (weight), and age (age). So you use SAS or SPSS statistical software and come up with the following output:
wt | age | dt | |
wt | 1 | -0.3 | 0.43 |
age | -0.3 | 1 | 0.5 |
dt | 0.43 | 0.5 | 1 |
The numbers in this matrix represent your correlation values (r). How in the world do you interpret this matrix? The rows symbolize the correlations for a particular variable. The columns represent the second variable being compared to the row. So for instance, the correlation between age and wt is -0.3. The correlation between dt and age is 0.5. Why is the correlation between a variable and itself ‘1’? Because the relationship between a variable and itself should bee 100% in agreement or 1. Why are we getting repeats of the numbers ? Because the comparison is in a matrix format. (Don’t look too deep if this is an introductory statistics course).
-Moore to follow- Amy