Same. I'd guess that ceteris paribus, comments based on statistical analysis would get more upvotes than anecdotes; it's just that ceteris ain't paribus.

A big part of a comment's karma is how many (logged-in) people read the comment, and in a given thread early comments tend to get more readers than late comments. Assuming that posting a statistical analysis is more time-consuming than posting an anecdote (and I think on average it is), comments with statistical analysis are systematically disadvantaged because they're posted later.

(This has definitely been my anecdotal experience. People seem to like comments where I dredge up statistics, but because I often post them as a thread winds down, or even after it's gone fallow, they're often less upvoted than their more-poorly-sourced parents.)