I wonder what are the recommended
count:poisson as objective in xgboost in R?
This is from XGBOOST documents: “poisson-nloglik”: negative log-likelihood for Poisson regression.
You might want to go and read more about poisson n loglikelihood.
Here is a link for you to get started: https://onlinecourses.science.psu.edu/stat504/node/31
Hope this can be helpful