tea-leaves.thumbnail.jpgJohn McCain is gaining in the polls nationally, according to several independent measures. The general consensus among political analysts is that McCain's relentless personal attacks on Obama are taking their toll. Obama's week-long vacation and McCain's saber-rattling during the Georgia/Russia conflict didn't help the Democratic candidate, either.

McCain pulled ahead of Obama in Reuters/Zogby's latest national poll, the results of which were released this morning. The live operator telephone survey of likely voters showed McCain leading Obama 46 percent to 41 percent--a spread outside the poll's three-point margin of error. An identical poll conducted last month had Obama in the lead.

Zogby breaks the results into subgroups including women, people over 35, Democrats, and Southerners. Interestingly, Obama support held up best among respondents making less than $50,000 per year.

Subgroup shifts are to political analysts what Giant Steps is to jazz musicians--an opportunity for flashy riffs. Analysts and consultants make their names, and their fortunes, by coming up with novel ways to interpret poll data. Everyone in the polling and interpretation game has a vested interest in claiming to see more complicated and interesting patterns than the next guy.

Also, keep in mind that the margin of error is greater when you look at results of sub-groups than for the sample as a whole. The smaller the sub-group, the greater the margin of error. For example, a survey of 1000 voters might have only 100 female evangelicals in it. If you compared what female evangelicals said last month to what they said this month, you'd be working with data from only 100 respondents, not 1000. So be skeptical of anyone who recommends major shifts in campaign strategy based on apparent movement within small subsets of larger polls.

The latest Zogby result is definitely an outlier compared to other polls taken during the same time period. Real Clear Politics' average of national poll results taken since August 4 shows Obama retaining a lead of 1.2 percentage points.

The latest LA Times/Bloomberg poll still gives Obama two-point lead over McCain, 45 percent to 43 percent. Note that this poll queried registered voters, as opposed to likely voters.

Obama still has an edge over McCain in the electoral vote, according to Real Clear Politics.

Update:  As one of my colleagues pointed out, the Rasmussen daily tracking poll through the last week gives Obama a stable 1 to 2 point lead over the past two weeks. Still not good news, but also more reason to question the validity of the Zogby results.