My records show a particular page of my web site was visited 609 times between July 2 and November 15.
Google Analytics reports only 238 page views during that time.
Given the time stamp of the last comment, I thought I'd leave an update here; Google Analytics recently announced they'd let people opt-out of Google Analytics, on the user-side, meaning if you didn't want website owners to track your movements, you could effectively become invisible on sites that are measured by Google Analytics. this could further offset your data points. in a sep thread, I suggested running two web analytics tools (many free to choose from) to measure against each other.