On Wednesday 10 October 2007, Steven Walling wrote:
You're trying to make an accurate judgment based on 100k of articles from a 2 million article field? Don't insult our intelligence.
That might insult your intuitions, but not a statistician's intelligence -- not that I'm one. If the sampling is random and we can make some standard assumptions, a 100K article sample size would be *overkill*, be it a 2 million or 20 million population.
On October 30, 2006 -- the last day for the WP Report statistics - I believe the number of new accounts created was 7940 . If we look at the previous 10 months the average is 9092 with a std. dev. 608. Robert says he notices -25% decrease, so I'm going to assume that's nearly 1985 less account creations or 5955 account creations in his sample.
Now then, what's the chance that Robert's value (5955) was simply the result of a freakish variation from his sample of a population that was continuing as it was, to say nothing of continued massive growth? (This is what I'm inferring you to be claiming.) Impossibly small. See: http://en.wikipedia.org/wiki/Statistical_power