search for: presenceabsence

...C is better, but what I am interested in is if statistically the increase in AUC from the glm model to the gam model is significant. I also read quite extensive discussions on the list about ROC and AUC but I still didn't find my answer. To calculate the AUC and plot the ROC I used the package PresenceAbsence. The help file for auc() says: " The standard errors from auc are only valid for comparing an individual model to random assignment (i.e. AUC=.5). To compare two models to each other it is necessary to account for correlation due to the fact that they use the same test set. If you are interest...

Hey, I am having trouble with lmer. I am looking at the presence/absence of water shrews against habitat and other factors e.g so I used this: m1<-lmer(Presencebsence~Habitatype*Width+(1|Sitename))summary(m1) But i keep getting this error up Error in mer_finalize(ans) : Downdated X'X is not positive definite, 16.> summary(m1)Error in asMethod(object) : matrix is not symmetric [1,2] What