I met someone at a conference and we had a good conversation. We emailed after for a bit. He is the associate editor of a reasonably well respected journal. He asked me to referee a paper and I just said yes without thinking much about it - he went to my talk and we talked for awhile so I assumed he knew what I knew well enough.
Now that I'm looking at the paper I have no clue what to say about it. I work in probability and this paper is straight up statistics. It uses a lot of jargon I am unfamiliar with and I have nothing valuable to say about the paper.
How should I proceed? I feel like my only honest review is "I don't know enough to judge the merit of this paper". I actually don't even like much of statistics and I'm uninterested in teaching myself the necessary statistics to understand this paper (which would require significant time and effort on my part).