eCPM increase after signing up for AdWords for my site?

[dualfragment]

My eCPM has been stable for 3 years right around the $1.50 mark. A week ago I signed up and starting paying for ads through Google AdWords. All of the sudden, my eCPM has doubled! Is this related or just a random coincidence? If a coincidence, what WOULD cause my eCPM to rise while my CTR stays the same?

[justbrowsing]

My guess is that your AdWords traffic is more targetted than your usual traffic. More targetted traffic = people more likely to be interested in your ads, and more likely to click on them!

[dualfragment]

My adwords traffic is less than 3% of my daily traffic...nowhere near enough to cause that much of a jump in eCPM. Regardless, my CTR has stayed the same...it was actually a little LOW today, about 0.5% less than normal.