I agree with Nicolas that the artist rank is more than the sum of albums and songs. One thing is if the artist writes his/her own songs. If not, I suppose that for most people the credit is spread between the writer and the performer. Then there's live performances and so on...

I also feel that for personal use the AM artist ranking formula weighs the top songs too high. For me personally, an artist with say 6 songs in the 2001-3000 region would beat an artist with one song in my all-time top 10 but nothing else that I enjoy. As plenty of people have already used the AM algorithm, I am surprised that no one has mentioned this before.