But not all surveys are equally trustworthy.

Thankfully there are a few telltale signs of untrustworthy pollsas well as polls you cankind oftrust.

Yeah, its a spectrum.

We talked to Jon Cohen, one of the most qualified poll experts in the country.

For the past four years, hes worked with new organizations to conduct polls aschief research officer at SurveyMonkey.

According to him, changing technology has actually made polling harder.

Calling cell phones can costtwice as muchas calling landlines.

So modern pollsters often have to use new methods.

Many news outlets cant afford their own polling, so they rely on outside polls.

There are more ways for a sloppy and inaccurate poll to slip into the media.

Meanwhile, experts in the field often disagree on polling methods.

Some of the industrys best standards have grown out of date.

(They explain their methodology here.)

And this is all between two sites that havepartnered up on surveys.

So the definition of a good poll can depend on which expert you ask.

The Solution

As old as the NCPPstwenty questionsare, theyre still a good starting point.

They include Who paid for the poll?

and What is the sampling error?

and questions aboutwho was actually surveyed.

(The NCPP elaborates on the implications of each answer.)

So with any poll, and especially any online poll, check how the respondents were selected.

If a single person changed their minds, that would shift your results by more than a percentage point.

(Cohen says that for rare populations, pollsters might settle for as few as 75 respondents.)

Knowing these can completely change the meaning of the results.

But the survey, funded by an anti-war donor, was engineered to get the desired answer.

There was no option for, say, troops leaving in two or three years.

Then when they run a poll with one method, they know how to adjust it.

There are tell-tale signs of an untrustworthy poll.

If a poll is reported with decimal points, Im very quick to dismiss it, Cohen says.

No poll, no matter how conducted, can achieve tenth-percentage-point accuracy on how people think.

If the shift had been half as large, they wouldnt have trusted the data enough to report it.

What do other polls say?Cohen believes that an imperfect poll is still often useful.

But its useful to compare it to other polls.

A well-done phone poll, even by a strong advocate, shouldnt necessarily be dismissed.

Averaged together, these partisan polls can still produce a useful result.

It would be nice to have more polls conducted and reported by unbiased third parties.

But thanks to the expense, there just arent enough of those.

So were left taking what we can from skewed, partially reported, or otherwise flawed polls.

(Out of thehundreds of pollstersthe site rates, it has only banned five.)

Better to take a flawed poll with the right grain of salt than to ignore it entirely.

The truth is that public opinion isnt a physical constant that we can precisely measure.

Its nuanced, hard to measure without influencing, and constantly changing.

So dont treat any poll as the infallible, timeless truth.