Earlier this year Mary Kelly (of Awful Library Books) wrote a really interesting piece about statistical analysis of collections on her blog The Practical Librarian (the original article, "Another Baby Step in Collection Analysis," can be found here). I thought it was quite useful except that it covered the average age of collections without talking at all about median age. I wrote a comment to that effect and now she has written a follow-up collection analysis post that does discuss the use of median age. The actual important things about this post are that first, it is very useful, and second, it is a good, concise explanation of the difference between mean and median. The self-important thing is that the post mentions my name and this blog! Mary is a pretty big deal in the public library world so it's sort of like an aspiring writer giving a suggestion to Neil Gaiman and him saying he thinks it's a good idea. I am pretty excited.
I know the audience of this blog is mostly non-library, but in case you are interested in truly professional librarian blogs, along with The Practical Librarian I would also recommend you check out The Swiss Army Librarian by Brian Herzog.
Awful Library Books and, of course, Love the Liberry remain my favorite blogs for library humor.