# How to interpret this normal qq-plot?

I have tried to fit a glm to some weather data and I got this weird qq-plot. What could this possibly mean? I am aware of how various skewed error distribution qq-plots should look like, but what I have here seems more bizarre.

• What kind of GLM was it? GLMs shouldn't necessarily have normal residuals (see here). – gung - Reinstate Monica Apr 16 '15 at 21:06
• What is nF? Is it a limited range DV? – iacobus Apr 16 '15 at 21:28
• Is this a possible duplicate? (However, gung's point is relevant; the interpretation may not matter much, depending on omitted details about the GLM) – Glen_b Apr 17 '15 at 4:53
• Is this maybe a Poisson regression with small counts? – Glen_b Aug 27 '15 at 7:35
• Simulate data from the estimated regression model, calculate residuals, repeat 1000 times, and plot those simulated residuals as a comparison distribution. Then we can see if this is typical residuals from your model, or not. There is in general no reason to expect normal residuals from an GLM. – kjetil b halvorsen Aug 27 '15 at 10:35

You've got some non-normal residual tails over there, especially a very heavy right one. Might want to consider taking a transform of your dependent variable. A log transform might help quite a bit, but no way to tell for sure without seeing the actual variable distribution, along with the rest of the residual plots (for both dependent and independent variables).