Consider a set of $100$ people, for each person we have 4 values which are: weight, height, age and the value of a medical exam, which will be called "A" for simplicity. I want to compute the correlation between weight and A, height and A and age and A.
Should I use one or two sided Pearson coefficient?
I computed the Pearson coefficient with the excel function (which I imagine is 1-sided) and the highest coefficient (all coefficients are >0) was the one of weight-A, about 0,077. But then I computed the 2-sided Pearson value with the help of this site http://www.wessa.net/rwasp_kendall.wasp#output and the coefficient of weight-A is the lowest (all coefficients are positive), the highest was the one of age-A, about 0,578.
What does it mean? Which coefficient should I consider?