PP Plot Interpretation?

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Posts: 1

PP Plot Interpretation?

I got this normal PP- Plot of regression, and just wanted to have its interpretation. The results on my plot are good fit or not??

Thanks in anticipation,

Respected Advisor
Posts: 3,054

Re: PP Plot Interpretation?

It seems as if you are fitting a discrete distribution to a normal distribution.

The results on my plot are good fit or not??

Impossible to say, without more context I would say this is a meaningless analysis

Paige Miller
Posts: 4,243

Re: PP Plot Interpretation?

I'd first look at the plot of residuals vs the explanatory variables(s) to see if the residuals have any pattern (not good fit) or seem randomly distributed (good fit). That will be a better indicator of whether the fit is good.

The P-P plot is used to examine whther the residuals are normally distributed, which is not the same thing as a good fit. The doc for PROC UNIVARIATE describes how to interpret P-P plots: Base SAS(R) 9.4 Procedures Guide: Statistical Procedures, Second Edition

As Paige Miller indicates, it looks like you have repeated data or rounded data, so your residuals cannot be strictly normal, but they appear to be roughly normal, given that constraint.

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