Thanks for all contributions to my question on normalising FA 0 inflated data. After reading your suggestions it seems that normality distribution can be skipped, even if it is being portrayed as important in fluctuating asymmetry data treatment. A clever point came from James Roper who suggested just exculding 0 data, which practically means symmetry of a treat; while our interest is to see the variability of asymmetry between traits/habitats. Nevertheless, even after 0 removal, and other further adjustments such as removing false directional asymmetry and trying different transformations the distribution was not normal for all traits/sites we considered . We therefore opted for nonparametric models as they can do just as fine. Dragos Zaharescu
Animal Anatomy Lab Faculty of Biological Sciences Vigo University, apd. 137 36310, Vigo, SPAIN [email protected] [email protected] http://webs.uvigo.es/zdragos/ ~ You should be the change you want to see in the world ~ Ghandi ________________________________ From: Adam T. Ford <[email protected]> To: Dragos Zaharescu <[email protected]> Sent: Tue, March 30, 2010 9:29:37 PM Subject: Re: [ECOLOG-L] normalization of zero inflated distribution Hello Dragos, I would use a Zero Inflated Poisson (ZIP) distribution with a generalized linear model in R. There is some great, accessible information in Zuur et al. mixed model book. Good luck, Adam On Tue, Mar 30, 2010 at 12:03 PM, Dragos Zaharescu <[email protected]> wrote: Is there any way of normalizing 0 inflated da > >Dear colleagues, > >Is there any way of normalizing 0 inflated data ? > >We work on insect fluctuating asymmetry (small, random deviations from 0 of >bilateral traits size) which for some traits show too many 0 (though this is >not bad). >Any comments are appreciated. > >Thanks >Dragos G. Zaharescu > > >Animal Anatomy Laboratory >Faculty of Biological Sciences >Vigo University, apd. 137 >36310, Vigo (Pontevedra), SPAIN >[email protected] >[email protected] >http://webs.uvigo.es/zdragos/ >Dragos > > > >Dragos Zaharescu >Animal Anatomy Laboratory >Faculty of Biological Sciences >Vigo University, apd. 137 >36310, Vigo (Pontevedra), SPAIN >[email protected] >[email protected] >http://webs.uvigo.es/zdragos/ > >~ You should be the change you want to see in the world ~ Ghandi > > > >
