Unifrac socre

Hi all,

when i use the command unifrac.(un)weighted to conduct hypothesis test , i know it’s better to do this with Amova or Homova , but still, i want to know the meaning of ‘UWScore’, is it same to dissimilarity distance ? or as the "unifrac.unweighted"says, “The significance of the test statistic can only indicate the probability that the communities have the same structure by chance.”?

i also get confused with the ‘UWSig’,the significance of the score ?

mothur > unifrac.unweighted(tree=abrecovery.paup.nj, group=abrecovery.groups, random=t)
Tree# Groups UWScore UWSig
1 A-C 0.703848 <0.001
1 A-B 0.722345 <0.001
1 A-C 0.623234 <0.001
It took 8 secs to run unifrac.unweighted.

thank you !

UWScore is the fraction of the total branch length in a tree that is unique to either sample you are comparing and is a distance. I strongly discourage the use of the unweighted metric since it is very sensitive to under sampling of communities. The better alternative if you want a “phylogenetic” approach is the weighted metric.