How shall one present LRT test statistic in a scientific journal ?
On Nov 26, 2009, at 12:14 PM, JVezilier wrote:
Hello !!
I'm recently having a debate with my PhD supervisor regarding how to
write
the result of a likelihood ratio test in an article I'm about to
submit.
I analysed my data using "lme" mixed modelling.
To get some p-values for my fixed effect I used model simplification
and the
typical output R gives looks like this:
model2 = update ( model1,~.-factor A)
anova (model1, model2)
Model df AIC BIC logLik Test
L.Ratio p-value
model 1 1 26 -78.73898 15.29707 65.36949
model 2 2 20 -73.70539 -1.36997 56.85270 1 vs 2
17.03359
0.0092
I thought about presenting it very simply copying/pasting R table and
writing it like: "factor A had a significant effect on the response
variable
(Likelihood ratio test, L-ratio = 17.033, p = 0.0092)"
But my boss argued that it's too unusual (at least in our field of
evolutionary biology) and that I should present instead the LR
statistic
together with the corresponding Chi^2 statistic since the likelihood
ratio
is almost distributed like a Chi2 (df1-df2), and then write down the
p-value
corresponding to this value of Chi.
I looked up in the current litterature but cannot really find a proper
answer to that dilmena.
So, dear evolutionary biologists R users, how would you present it ?
I am not an evolutionary biologist, but presumably your supervisor is one. Why are you picking a fight not only with him but with your prospective audience when there is no meaningful difference? Here is the p-value you would get with his method: >> 1-pchisq( 2*(65.36949 - 56.85270), df=6) [1] 0.009160622
David Winsemius, just a guy who formerly argued about such matters. > > Thank you very much, > Julien. > -- > View this message in context: http://old.nabble.com/How-shall-one-present-LRT-test-statistic-in-a-scientific-journal---tp26532480p26532480.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > R-help at r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. David Winsemius, MD Heritage Laboratories West Hartford, CT