Question: Different calculation of Bray-Curtis dissimilarity in vegan (R) and mothur?

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songzewei •

**0**wrote:The Bray-Curtis dissimilarity using vegdist of the vegan package in R is calculated as the sum of absolute difference between each pair of OTU:

`bray` |
d[jk] = (sum abs(x[ij]-x[ik]))/(sum (x[ij]+x[ik])) |

binary: (A+B-2*J)/(A+B) |

But this is different from what is described in mothur (http://www.mothur.org/wiki/Braycurtis ), and wiki (http://en.wikipedia.org/wiki/Bray%E2%80%93Curtis_dissimilarity ), which use the sum of minimum abundance of each pair of OTU.

Are they the same mathematically?

Thanks!