Re: [R-sig-eco] Dissimilarity measure for rank data

2017-06-08 Thread Hanna Tuomisto
Hi Tania, Even though there is no perfect answer: don't use the combination Hellinger transformation + Bray-Curtis distance. The appropriate combination is Hellinger transformation + Euclidean distance, which gives you Hellinger distances (this is an asymmetric dissimilarity measure, which does

Re: [R-sig-eco] Dissimilarity measure for rank data

2017-06-08 Thread Sarah Goslee
Hi Tania, That's not really an R question, and there's no one perfect answer. Googling "distance metric for ordinal data" turns up some discussions of the pros and cons of the various options. You need to choose the one best able to address your hypothesis. You might get better ideas on a statist

[R-sig-eco] Permanova for microbiome analysis with repeated measures

2017-06-08 Thread Ricardo Ramiro
Dear all, I have the following experimental design: 9 mice (mouseID) were assigned to three different treatments (3 mice per treatment level) and we estimated the composition of microbial species in the gut at 5 time points (same time points for each mouse). I would like to know if the community d

[R-sig-eco] Dissimilarity measure for rank data

2017-06-08 Thread Tania Bird
I have species data that I would like to use for ordination. With regular abundance data I would apply a Hellinger Transformation and then use the Bray-Curtis distance. Since the data are ranked (0 to 5) I will not transform it. But what dissimilarity measure should I use instead of Bray-Curtis?