I am fitting the following model in "mgcv" package in R using option
family=betar to predict a percentage cover response variable (
g6 = gam(cyano/100 ~ s(SEGLOWFLOW) + s(SEGJANAIRT) + s(LOCHAB) + s(LOCSED) + s(T2PastoralHeavy) + s(SEDO) + s(USDAYSRAIN) + s(USAVGSLOPE) + s(USHARDNESS), data=nati1, family = betar(link='logit'))
I get the following warning message:
Warning message: In object$family$saturated.ll(G$y, wts, theta) : saturated likelihood may be inaccurate
The summary output gives me negative explained deviance values:
R-sq.(adj) = 0.0871 Deviance explained = -29.9% -REML = -2370.5 Scale est. = 1 n = 463
Although the diagnostics plots (
gam.check) look fine and the predictions make sense, I am worried about the warning message and the negative deviance explained value.
Any thoughts will be appreciated.