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I have a simple poisson glm with one predictor that has three levels. Unfortunately, for one level my response, the variable has only counts of zero. I expected very low counts (perhaps a one or a two at most). Because of one level having all zeros, neither my poisson glm, nor "zeroinfl" (from pscl), work. The glm throws out a massive standard error for the all zero factor level and the zeroinfl gives me an error message.

Is there a statistical way to say that the other two groups are different from the one with all zeros?

kjetil b halvorsen
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whatbehaviour
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    I'm voting to close this question as off-topic because it seems abandoned and OP is not longer on site to answer necessary followup questions – kjetil b halvorsen Aug 10 '18 at 21:04
  • @kjetilbhalvorsen This question can quite happily be closed. Is that something I should have done myself? I left it open in the hopes that someone would have an answer for me. Honestly, though, I had given up on ever getting any response. I am around, but had forgotten that I had this account. Recently I have been using a different one. – whatbehaviour Aug 12 '18 at 17:19
  • Please merge your accounts (you can find information on how to do this in the **My Account** section of our [help]). – gung - Reinstate Monica Aug 12 '18 at 19:34
  • I suspect this is answerable. Can you post a small example dataset? – gung - Reinstate Monica Aug 12 '18 at 19:37
  • I will go merge my accounts. I didn't know that was possible. I can't remember which data set I wanted to ask about 4 years ago, but it is something that crops up quite a lot. I'll have a look when I get to work tomorrow. – whatbehaviour Aug 14 '18 at 17:49

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