I performed a multiple linear regression and after checking my results everything seems to be great, but when I checked the residuals I noticed this patterns in the attached figure and I am not sure if it's right or not. I think there are two (or maybe three) groups. Am I right? Or this is a a random distribution? If there are two or more groups, what should I do next?

Thanks!

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#### Best Answer

You seem to have 3 groups of predicted values. This looks like you have one categorical predictor that takes 3 levels and one or more continuous predictor, but that the categorical predictor has a stronger relationship. That is not, in itself, a problem. But if the residuals are related to the fitted values, that is a problem. However, you have so little data that it is hard to tell.

The fact that you have so little data makes me worry about overfitting.

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