Most people don’t know how to interpret a poll, and that includes virtually all reporters and pundits — even the conservative-friendly ones. Let’s face it. For most people, their eyes start to glaze over once you start talking about “internals,” “turnout,” “demographics,” and other such esoteric stuff. They are interested only in the top line.
I tear into every one of these polls because I want to find a single poll that actually shows Obama ahead by a statistically significant margin in a sample that actually reflects a representative sample of likely voters. I haven’t seen one yet. The only polls I’ve seen that favor Obama either do not publish their internals or are clearly oversampling Democrats based on actual exit poll data and realistic turnout models.
Karl used to say that a personal appearance in a state could bump poll numbers by 2 or 3% in one's favor. IF McCain is spending alot of time in PA it must mean that he sees an good opporunity it steal a blue state.
Also, if McCain is down by 2 in PA, it means that he is closer nationally than the media polls suggest. After all, Bush lost PA by about 2% in 2004. So, this means that he is doing better in states like OH, VA, NC and FL than some pollsters suggest.
These national polls will also trend in McCain's direction as the election gets closer. They want to be accurate in the end. And remember that about the only people that follow these things real seriously are the political geeks that frequent sites like this one.