Damn Lies And Cat Statistics

[shmoo]

http://www.sfgate.com/cgi-bin/article.cgi?...tscol081810.DTL

Did you find yourself hip-deep in cats the last time you left the house?

No? Neither did I. But if the so-called "facts" about feline reproduction that humane organizations, animal lovers and the media spread with zeal were true, we'd need feline-resistant biohazard suits just to cross the street.

Take this statistic, once published by the Humane Society of the United States and the American Society for the Prevention of Cruelty to Animals and still zealously spread by many local animal welfare organizations and cat spay/neuter advocacy groups: The offspring of a single unspayed cat will, within five years, add up to 420,000 cats.

Four years ago, pet columnist Gina Spadafori ran those figures past Carl Bialik, the Wall Street Journal's "Numbers Guy." He has a degree in mathematics and physics from Yale University, and his column routinely examines the basis of statistics used in the media.

"The numbers didn't add up to me," Spadafori said. "And it turns out they didn't add up, period."

Bialik did the math in a couple of different ways, and consulted a number of experts in veterinary medicine and wildlife management. The real number? Somewhere between a low of 98 and a high of 5,000 cats in seven years.

Today, neither HSUS nor the ASPCA use the higher number on their websites; John Snyder of HSUS called the number "flawed" and told Bialic, "I have no idea where that number came from." The ASPCA, for its part, said it had gotten the stat from HSUS, and agreed with Bialik that the number was wrong.

Nonetheless, a search for "unspayed cat 420,000" will clearly demonstrate that this particular falsehood has developed a life of its own. I found the flawed statistic quoted by countless organizations, including the Michigan Humane Society, Operation Pet Fix, and AdoptAPet.com, a high-profile advocacy project sponsored by Purina, Bayer and the North Shore Animal League.

So why do so many humane societies and animal advocacy groups keep insisting that one single unspayed female cat can produce something like 420,000 offspring in just five years? And why do so many pet lovers believe them, and keep repeating it?

Those are the questions that drove Peter J. Wolf to create Vox Felina, a blog dedicated to examining the basis of claims made about cat numbers and behavior, and debunking those that don't withstand scrutiny.

Wolf, a mechanical engineer and professor of industrial design and visual communication at Arizona State University, is a life-long cat lover. After his involvement with the rescue of around 900 cats from a bad situation in Nevada, he began to do research into the feral cat problem, particularly into successful and unsuccessful attempts to manage it.

"I kept coming across some very dubious claims," he told me. "And the more I'd dig into them, the worse it got. You'd start out thinking there was broad support for a particular claim, but you'd start drilling down a little bit and see all the references supporting that claim pointed to the same flawed study. So this 'broad support' became questionable."

Like Spadafori four years earlier, Wolf turned to Bialik at the Wall Street Journal to help him understand the problem of what he called "sticky numbers," or statistics lacking a scientific basis that nonetheless gain wide traction in the media and among advocates for or against various public policy proposals.

He quoted Bialik as saying in a column, "An interesting phenomenon of these numbers is that they'll often be cited to an agency or some government body, and then a study will pick it up, and then the press will repeat it from that study. And then once it appears in the press, public officials will repeat it again, and now it's become an official number."

Bialik wasn't talking about cats in this particular column, but Wolf saw the same phenomenon playing out in the often acrimonious public debates over managing feral cats.

"Take the estimates of how many birds are killed each year by cats," he said. "A 1993 article usually called 'the Wisconsin study' is constantly being cited, with an estimate that between 8 and 219 million birds were killed by free-roaming rural cats in that state."

But 15 years ago, study co-author Stanley Temple told the Sonoma County Independent, "The media has had a field day with this since we started. Those figures were from our proposal. They aren't actual data; that was just our projection to show how bad it might be."

Despite that apparently definitive disclaimer, Wolf discovered that the study and those numbers are still being cited in such publications as the New York Times (2007) and the Journal of Conservation Biology (2009). Even the U.S. Fish and Wildlife Service cites the study, he said.

Wolf attributes the "stickiness" of some of these feline statistics to a number of factors. "There will always be those people who hate cats and will look for any excuse at all to justify their attitudes," he said. "But that's not the whole story."

People often become overwhelmed with the complex reasons behind the destruction of habitat and wildlife. "Things like clearcutting that really contribute to songbird losses aren't even on this continent, let along something people feel they can do anything about," he said. "It's much easier to focus on something they feel they can get a handle on, such as rounding up and killing feral cats."

But the real problem, he said, is that a false statistic is very simple to express, and the explanation as to why it's wrong can be very complicated. "It's very easy for someone to make an argument that's bumpersticker-sized," he told me. "Saying cats kill one billion birds is the kind of thing that rolls right off the tongue. A 15-second news spot can cover it. But it takes a couple of episodes of 'Frontline' to dispute it."

Worst of all, said Wolf, "Complex arguments don't combat sound bites well. You end up sounding like conspiracy theorist on late night radio."

Of course, this isn't just a problem in the cat world. Pulitzer-prize winning science writer Deborah Blum feels Wolf's pain, too. Blum, a journalism professor at the University of Wisconsin - Madison, said, "In science journalism, we spend a lot of time looking at this particular problem. Why do some numbers get this bizarre traction? Why do people believe it, when if they did a little digging they'd find it's not only wrong but in some cases even does harm?"

One reason, she told me, is that there's a whole PR machine behind many research studies today.

For example, she said, "A few years back there was a study done by Ohio State University. It found that when interviewed about the kind of women they'd like to date, the majority of men said they preferred secretaries to bosses."

Inflammatory? You bet. Media fodder? That too; it sparked plenty of coverage, including a column by the New York Times' Maureen Dowd, and Blum was asked to comment on it for a radio show. But when she took a look at the actual study, what she found was far different from what the press was reporting.

"The question they asked was not whether men would rather date bosses or secretaries," she told me. "It was whether they'd be more attracted to a women who could tell you if you could go to the bathroom or not, or a women who brought you coffee."

Of course, most people don't do what Blum and Wolf do, and read the actual studies being cited and reported in the media or during public policy debates.

"We get gamed by the system because institutions and government agencies are promoting themselves, and most people haven't taken a statistics class, and aren't professional science journalists with all this time to wallow around in a scientific paper," Blum said.

She cautions against believing numbers without some kind of understanding of where they come from.

"There's some outstanding work out there, and sometimes numbers give us a valuable portrait of what's going on," she said. "But if you're talking policy issues that affect the lives of people and of animals, that influence our lives in an everyday sense, you have to realize that numbers can be deceptive in their simplicity, and often tell a false story."

Getting back to cats, why does this matter? Tall tales about rampant feline reproduction and predation rates, and their persistence even after being debunked or challenged, can be a matter of life and death for feral and free-roaming cats. If large numbers of people believe -- and convince public policy makers to believe -- that a single unspayed cat can produce 420,000 descendents in seven years, and that cats kill a billion songbirds every year, it becomes very easy to argue for the mass trapping and slaughter of free-roaming cats in the name of protecting birds.

Cat advocates obviously don't want to see that happen, so the fact that they're often the very ones quoting the 420,000 number is particularly ironic.

But bird advocates shouldn't want to see it happen, either. After all, public policy based on bad data is going to be ineffective, and if your bird protection plan is based on a lie, it's not going to save the birds whether you get rid of the cats or not.

"You end up spending all your time fighting over some statistic," said Wolf. "Which means you're not having the discussion that will move the issue forward. You're getting mired down in a process that can never result in an actual solution to the problem."

[Zhou Xuanyao]

Good article. The organizations who have been perpetuating these figures simply discredit themselves in their persuit to (presumably) promote desexing.

When the truth comes out everyone will view anything they say with greater skepticism in the future, so they have hurt their cause with their irresponsible use of bad information.

Worst of all, said Wolf, "Complex arguments don't combat sound bites well. You end up sounding like conspiracy theorist on late night radio.

Unfortunately his right.

Edited August 20, 2010 by Lo Pan

[Staranais]

Sounds like the person who made up that statistic either intended to deceive people or was perhaps just bad at maths. But surely even producing 98 to 5000 kittens in a lifetime is a great reason to desex a female cat?

[Christina]

Cats have had all kinds of persecution & weird things attributed since time began from the bizarre to the ridiculous.

Campaigning for desexing should be based on the welfare to the cat.

The most destructive species on the planet is human beings, in every form imaginable.

How many of this dreadful species can one mans sperm produce ? Should we desex this species ?

All rather ridiculous really.

[Souff]

Good to see somebody not believe all the rubbish that has been promoted by some.

Wouldn't mind at all if these anti-breeding people could turn their zeal to the mass sterilisation of rats though, just leave some nice tasty morsels out that are laced with a drug that will permanently sterilise rats. Horrid things that do multiply very quickly and are becoming very cagey about going into traps.

Souff

[Debyork2]

Oh no-not poor ratties! I have two pet rats and they are delightful, and despite all the bad press they get they are very clean-they even wash their 'hands' and faces in their water bowl after they've eaten!! Cats get bad press too-so many people seem to have an unreasoning hatred of cats for some reason, as another poster said it's humans that are the problem.

[sandgrubber]

How many litters can a cat have a year? How old does she have to be to have kittens? What is the average number of kittens in a litter? How old does a queen need to be to have her first litter.

I tried to do the math on this one assuming six kittens per litter, three of them females, two litters per year, fertile at six months. The numbers shouldn't add up . . . it's multiplication . . . and offers the potential for exponential growth, which often leads to explosive projections which can range from tens of thousands to multi millions depending on a few initial assumptions. For me the math wants to come up to a very large number. If you count not only the queen, but also all her progeny and her progeny's progeny, you can come to a number approaching 500,000 in the sixth year; change the assumptions and you end up with hundreds of thousands more or less. The most important, and most absurd, assumption you have to make to get a very large number is that all kittens survive and reproduce. Of course, most barn kittens die without reaching adulthood, and most owned house cats get speyed before they have a litter . . . or shortly after the first litter. Few families want to go through with a second litter. On the other hand, a ferral cat in an area rich in rabbits may succeed in raising litter after litter, and her kits may also succeed, for many years, ending out with enough cats to begin keeping rabbits in check, and more than enough cats to decimate native animal populations.

I think people are being too hasty to dismiss the RSPCA's comments about cat fecundity. We aren't confronted with unwanted kittens everywhere because a large fraction of cat owners get their girls speyed. Personally, I'm glad that's the case.

Btw, the issue is one of projections, not statistics or facts. Projections vary greatly depending on the assumptions made in the model used to make the projection.

Edited August 24, 2010 by sandgrubber