I'm working on a project where we want to estimate how many of a particular bird species there potentially could be in every 10-km square in England. For this I want to use quantile regression to get a 0.90 quantile estimate rather than the mean and so better estimate the possible abundance rather than the current abundance. However, I have count data as my dependent variable and all the quantile regression packages I can find in R seem to require normally distributed data. I also need a weight in my model to account for survey effort and again only some packages allow this.
I thought the qgam package might be the solution but that does not allow you to specify family and instead uses a family called "elf". I've tried reading about elf and found it's the extended log-F family, but I'm an ecologist not a statistician and I found myself lost in the equations!
So my questions are:
- Can anyone explain the elf family for me in a simple way?
- Is the elf family suitable for count data?