However, I think it’s more important for a stats package to be internally consistent than to be partially accurate. For example, lets say I’m comparing Google.com and Yahoo.com in comScore. Hypothetically, comScore has a pixel on Google’s page, but not one on Yahoo’s page. I’d rather comScore report to me the panel-extrapolated data for both Google and Yahoo than the pixel-logs for Google and the panel-extrapolated data from Yahoo. Any errors in methodology will come out in the wash in a side-by-side comparison as long as the methodology for report both stats are internally consistent.

But, it would be create if comScore created some kind of “pixel-outreach” program to improve their ability to extrapolate from a panel. But, my gut says they’re probably already doing this.