MCSE certification hurts salary? really?

This blog post discusses how MCSE holders aherage $10K less than people who hold no certification. "The title is a little misleading, but this article is a pretty interesting read."

Actually, statistical analysis shows that those numbers mean little for the person trying to decide whether to get certified. It stands to reason that people who feel the need to get MCSE are less credentialed (or otherwise less successful) than those who do not - no-one who was just promoted to a development manager, for example, would have the time or inclination for a resume-building effort. It is those who did not get the promotion/job/assignments they wanted who will. And those are just the people who would be paid less.
Yet, stands to reason isn't statistics, and reason is often wrong. My take? inconclusive. an interesting double blind would be to have half of a group (randomly chosen) get certified, and the other half not, revisit them in 2 years and see their salary delta. Double blind? not quite, but almost. Is this experiment going to happen? I thinketh not.