There's been considerable confusion about which trial heat results to pay the most attention to at this point in the race. Here's my take, which should help clarify why I choose to focus on certain results over others in this blog.

One issue is likely voters (LVs) vs. registered voters (RVs). At this point, most polls are surveying only RVs and I believe that's appropriate and, in fact, preferable. It is way too early to put much faith in likely voter screens/models as representing very accurately the voters who will actually show up on election day. There is reasonable evidence that careful likely voter methodologies work well close to the election and do fairly accurately capture that pool of voters. But there is no such evidence for LV samples drawn this far out.

Indeed, my understanding is that Gallup does LVs this early not so much because they believe they are capturing election day voters this early, but more so that they can avoid having to explain sudden shifts in the horse race question as LV data replaces RV data in the fall (the traditional time to switch from RVs to LVs). There have apparently been some problems with this in the past, so reporting both from the very beginning of the campaign eliminates any potential embarrassments along these lines. But that doesn't mean the LV data is any better at this point in time--it merely means they're providing it.

In fact, since the sample size for LVs is smaller and since the composition of the LV sample will shift depending on how political developments are affecting interest and intensity levels among different groups of voters, additional volatility is built into the LV samples that is not there with the RV samples.

And then there are the comparability problems. LV samples are difficult even to compare to one another, since methodologies differ, and clearly can't be compared very well to RV samples, which are the bulk of polls at this time. That's another strike against paying much attention to LV results this early.

Another issue is how much attention to pay to the Rasmussen tracking poll. My view is that this poll is worth looking at but with caution. It is the only tracking poll out there at this point and therefore on any given day it may have the "freshest" results. But it is only one poll and there is no other tracking poll to check it against. Moreover, it is a poll of LVs, which, as outlined above, should be viewed with some skepticism at this point. Therefore, I am inclined to pay more attention to standard national polls of RVs and the trends these polls imply than to this one tracking poll.

Let me sum up my current approach, both as outlined above and in previous posts (for example, on the Bush-Kerry vs. Bush-Kerry-Nader question) with the following:

Ruy's Rules

1. Pay more attention to Bush-Kerry results than to Bush-Kerry-Nader results.

2. Pay more attention to RV results than LV results.

3. Pay more attention to recent national polls of RVs and the trends they imply than to the Rasmussen poll.

These rules don't mean ignore the rest of the data. On the contrary, immerse yourself in as much of it as you can stand. But these rules provide a way to sift through the available data to get the best sense of how the contest between Bush and Kerry is developing.