I'm writing my master thesis and have a problem with a multiple linear regression analysis:
I have a non-linear relationship between the independent and dependent variables, as you can see in the picture of the partial regression plot (showing the relationship between one independent and the dependent variable, the others look quite similar). So the condition for a regression is not met. My question: What can I do?
I have tried the transformation of the variables, but that didn't work. I have read that there are also non-linear and non-parametric methods. But most of them are not supported by SPSS. Thats all I know with my very basic and limited knowledge in statistics.
For my thesis I would like to know, if there is a "easy" way to analyse my data. If not, I would need a good explanation, I guess.
Ah and by the way, I have two samples (same problem) I want to compare. Maybe I could use the regression to compare both samples nevertheless?
I hope you understand my issue and can help me. Thanks :)