I have 5 numerical variables (same units) (A, B, C, D, E and F) for N=13 countries.
We could say I combine the variables into a composite variable called A. The formula is : A = (B + C + D + E + F) divided by 5.
I want to know which variable between (B, C, D, E or F) is the "most important", I mean which one contributes the most in explaining A. I am asking that question because as we can remark the variable "A" is strongly related to the 5 other variables. To answer my question, I have planned to calculate the squared Pearson or Spearman semi-partial correlations. Do you agree ? If not, what would you do ?
In my opinion, I can combine the variables into a composite variable. There is a downside to this approach in that each of the five variables has measurement error. Thus, the composite includes the combined measurement error for all five variables. Does this perturb the use of the squared semi-partial correlation ?
By the way another problem is that the same variable appears on both sides of the equation, so we are correlating a variable with a composite variable that contains the same variable. This will inflate the semi-partial correlation ?