Script which pulls out correlations of crashes against specific graphics hardware. Based largely on Selena's queries from bug 845970, but without multiple table scans by reusing the "BySignatureGraphics" CTE for all the joins.

Not complete; lots of hardcoding here needs to be fixed, and I'm going to experiment with correlating against "installs" instead of raw crash counts.
Remove commented-out columns unnecessary to the final query.
Add an alternate way of calculating correlations by "install" instead of by total crash count. See the comment before q2 explaining when you might want to use one or the other method.
Fix "q" by adding the extra column.
The latest code.
Make the script write both the bycrash and byinstall versions of the data. Parameterize the queries by startdate and product_version_id so that we can use this on other versions.
Make the graphics correlations paramaterized.