Mark Blumenthal | July 9, 2008
Topics: AP/Yahoo Poll , Associated Press , Barack Obama , John McCain
Yesterday, the Associated Press wrote up results from an AP/Yahoo poll showing that John McCain does better than Barack Obama among pet owners than among Americans who do not own a pet. Desmoinesdem, the blogger who seems to have a knack of getting called by internal campaign polls, called it "the worst analysis of a poll I've seen in a while." I tend to agree.
The gist is that a survey of 1,750 adults conducted over the Internet using the Knowledge Networks panel found that John McCain leads by Barack Obama by five points among pet owners (42% to 37%), while Obama leads by 14 point margin (48% to 34%) among those who do not own a pet.
They also report results showing Obama doing slightly better among cat owners than dog owners, although those differences to do not appear to be statistically significant -- something the AP story does not mention.
Go to the end of the story and you get a hint of something highly pertinent:
The population breakdown of who has pets and who doesn't also may be a factor.
For example, the poll found 47 percent of whites own dogs, compared with just 24 percent of blacks. Whites tend to favor McCain, while blacks overwhelmingly favor Obama.
Some 64 percent of dog owners are married, slightly higher than the overall population. The poll found 47 percent of married people own dogs, compared with 39 percent of non-married people. Married people tend to favor McCain.
Married people also "tend to" be over the age of 30. As Gallup tells us, Obama leads by a whopping 24 points among those age 18-29, while the race is much closer among those over 30.
And what about pet ownership by party affiliation? Or income? As Demmoinesdem points out, these potentially confounding variables may also be at work. And that strong possibility reminds us of the lesson that all pollsters are supposed to learn in their first statistics class: Correlation is not causation. Pet owners may prefer McCain for reasons that have nothing to do with whether the candidates own pets.
But that lesson is largely lost in this piece, because in the lead of the story -- and who knows how many local television news pieces run as a result -- strongly implies just the opposite (emphasis added):
If the presidential election goes to the dogs, John McCain is looking like best in show.
From George Washington's foxhound "Drunkard" to George W. Bush's terriers "Barney" and "Miss Beazley," pets are a longtime presidential tradition for which the presumed Republican nominee seems well prepared, with more than a dozen.
The apparent Democratic nominee Barack Obama, on the other hand, doesn't have a pet at home.
The pet-owning public seems to have noticed the difference.
Really? Do we have any evidence that Americans have "noticed" the difference? How many know that McCain owns "more than dozen" pets while the Obamas own none? Which candidate do Americans consider more pet friendly? This survey is silent on that score.
Even without probing deeper into the subject, a fairly simple regression analysis would tell us if pet ownership shows a significant correlation with vote preference even after controlling for things like party, race, age, income and marital status. And while we would not expect an AP story to expound on multiple regression analysis, they could certainly tell us, in so many words, that pet ownership explains greater preference for Obama even after controlling for factors like party, race, age, income and marital status.
That might be a start, but why let a straightforward analysis kill an irresistibly cute lead?