Interpreting Pairwise and Bhattacharyya coefficient Comparisons

[Grant Dlesk]

Hi,

I don't know if this group is only for troubleshooting or for interpreting results as well. So I apologize if this wrong place for this question.

My question was if I have a relatively high pairwise comparison (>=) value for one of the groups in my data (0.62), but it and the group it is compared to have a Bhattacharyya coefficient value over .90. Does that mean the posterior distributions overlap so much that the is no significant difference in trophic position between the groups? 

Context:

My data is from two species of invasive crayfish  (rusty, and red swamp) and zebra mussels collected from a section of the Chicago River with the zebra mussels serving as the baseline. There are sections where only one of the species of crayfish occurs and sections where they overlap. We are investigating if the red swamp crayfish have a higher trophic position than the rusty crayfish when they overlap. We collected crayfish in three zones A, B, and C with A and C being areas with only rusty and red swamp crayfish respectively, and being the area with both species. 

I used the one baseline model and was following the Finnish Fish example. Our results from the posterior trophic position graph showed that rusty crayfish were slightly higher than red swamp crayfish in zone b where they overlap. The rusty group had 0.62 in the pairwise comparison with the red swamp in the same area having a 0.38, but both groups had a Bhatt value of 0.978.

In zone C with only red swamp crayfish there is a large increase in trophic position which I believe is attributed to the crayfish and mussels being collected in an area below a large water reclamation plant, which is likely enriching the d15N values of both of them.  

I will attach the graph to this message as well.

Thanks,

-Grant