# [R-sig-ME] comparing heritabilities of traits

Mon Feb 14 11:40:20 CET 2011

```Hi Ardo,

I think I have addressed some of these questions in reply to some of
your previous posts to the list. In short, testing the 'significance'
of a heritability estimate is difficult to evaluate from the posterior
because it has to be positive. I've seen people use DIC to evaluate
whether a genetic term should be included, but I think DIC is
'focused' at the wrong level for this sort of question and people
should be very wary. My personal view is that a significance test for
h2 is meaningless (everything that varies between individuals in an
outbred population will have some genetic variance, even if it is
small) and that people should focus on the width of the credible/
confidence intervals rather than the p-values.

With regards to your second question about how to choose the trait
with greatest h2, you could try this:

h2<-function(x){x["animal"]/sum(x)}  # calculates h2

h2.post<-as.data.frame(lapply(list(m1=m1\$VCV, m2=m2\$VCV, m3=m3\$VCV),
function(x){apply(x, 1,h2)}))

# create a table of posterior h2 for each response (m1, m2, m3 .....)

prop.table(table(apply(h2.post, 1, which.max)))

# posterior probability for each response that it has the highest h2

Cheers,

Jarrod

On 11 Feb 2011, at 16:02, Ndjido Ardo BAR wrote:

> HI list!
>
>
> I'm using MCMCglmm to estimate heritability of candidate traits so
> as to
> select the most heritable ones for further genome wide association
> study. My
> problem is to establish the significance of those heritabilities being
> different to zero and to compare them. I do have HPD intervals but i
> dont
> know how to decide!
>
> cheers,
> Ardo
>
> 	[[alternative HTML version deleted]]
>
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