I am testing whether price per ounce of beer (continuous variable, range of values mostly between 0.1 and 0.5 dollars) and the presence of promotion, advertisement, and display (all binary) have effect on the total amount of ounces purchased (continuous variable). Here is my residual vs. fitted plot before the log transformation of y:
This is the residuals vs. fitted plot after the log transformation of y:
Heteroskedasticity is very high (White's general t statistics is nearly 800).
This is the histogram of the transformed y:
Any ideas or suggestions on how to improve my model or where to look for errors in order to improve the problem of heteroskedasticity are greatly appreciated.