I have some problem with the transformation of my data. This is my project in my regression class, and we're asked to run our data and satisfy all the possible assumptions, until we can chose a model. Which we're going to use for prediction. Now, I tried all possible transformations, but It doesn't give me any solution to make this scatter plot linear. Or is there any test that I can use to check the linearity of my data? Than using informal method of looking to the plot only.
Well, Here's the plot image of Residual versus the Fitted Values.
I tried log-transforming, modifying my regression function, and etc. But still it doesn't make linear.
Though, I check the constancy of my error variance using the Breusch-Pagan test, which concludes it to be constant.
But, I don't know any other test for checking Non-linearity.
I really appreciate your help.