I have a response variable of percent cover of vegetation in a quadrat. I have tried to arcsine squareroot this data as recommended in the Crawley R book but I am not getting good fit. The data is zero-inflated with about half the data points being zero. Can someone point me in the right direction for how to approach building this model? I am striking out on Google.

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    $\begingroup$ Not clear what model you seek here as you don't make it clear what predictors you may or may not be using. But in general if there's a spike in a distribution, there is a corresponding spike in the distribution of any transformation of it; that's inescapable. There are models for zero inflation of various response distributions; here you might want zero inflated beta. $\endgroup$ – Nick Cox Nov 25 '13 at 17:21
  • $\begingroup$ Regarding the arcsine transformation, perhaps you could read the paper Arcsine is asinine before continuing this line of investigation? A free PDF version is here. Also, this previous Cross Validated discussion would seem of relevance: $\endgroup$ – Reinstate Monica - G. Simpson Nov 25 '13 at 17:27
  • $\begingroup$ As for R software for zero-inflated beta, try the gamlss package. Also take a look at the VGAM package as it may be able to do this as well. $\endgroup$ – Reinstate Monica - G. Simpson Nov 25 '13 at 18:07
  • $\begingroup$ You may try the pscl package in R. $\endgroup$ – overwhelmed Mar 20 '14 at 9:34

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