# Calculating group differences

Hi everyone,

I am trying to compute the overall posterior differences between groups (A - B = 0) from a `brmsfit` object using the `hypothesis` function but I am unsure I am performing it correctly with the interaction term so I would love a bit of advice.

The structure of my model is as follows:
`prop_mod=brm(prop_links~0+PolOrder*clim+(1|Reference/Network), family=Beta(link = "logit"), inits=0, prior=propprior, data=g.sub,cores=4)`

`Prop_links`= proportion of network links
`PolOrder` = Pollinator insect order (6 groups: Bee, Coleoptera, Diptera, Hymenoptera, Lepidoptera and Syrphidae)
`clim` = Climate zone (5 groups: A, B, C, D, E)

As such, I am interested in differences between `PolOrder` group within each `clim`.

With considering `climate A` (the reference level of `clim`) I have performed the following when considering bees (the reference level of `PolOrder`) with Syrphidae:
`hypothesis(prop_mod,alpha=0.05, c("PolOrderBee - PolOrderSyrphidae = 0")`

And within a different `climate` I have done as follows, adding in the interaction:
`hypothesis(prop_mod,alpha=0.05, c("(PolOrderBee + climB) - (PolOrderSyrphidae + climB + PolOrderSyrphidae:climB) = 0"`

These appear to give me sensible results but id love some clarification as similar posts I have read arenâ€™t exactly like my case.

Also, am I missing something in the `hypothesis` output or is it possible to get a numeric value how far the expected value under the hypothesis lies outside the 95%-CI as well the *