I am trying to fit a simple linear model with OLS. I have say 4 terms and the number of data points is >> 4, so no explicit overfitting.
1) My terms or my independent variables do have a strong correlation among each other 2) They are all positively correlated with my y
My question is that on building the OLS model, I actually see the coefficient on some independent variables to be negative.
I was expecting all positive signs actually, given the positive correlation. What could cause this? What is a remedy, Non Neg Least Squares.