Daryl Cagle, MSNBC cartoonist

In defending its actions in screening passengers, the TSA continually points to a CBS News Poll which claims that 80% of Americans support the scan. What does that really mean?

Let’s take a look at the actual question that was asked:

Some airports are now using “full-body” digital x-ray machines to electronically screen passengers in airport security lines. Do you think these new x-ray machines should or should not be used at airports?

Nowhere in the question is the technology explained. No mention of the fact that the scanners see through clothing and generate images that provide anatomical detail. No mention that the efficacy of the scanners has been questioned by security experts. No mention of the potential health effects of the x-rays. The frame of reference that most people have for x-rays is what they see at the doctor’s office when they break a bone. People are being asked a question without the background to understand what it really means.

The poll also surveyed the general population. It does not reflect the population that actually flies, even sporadically. (Much less those who are on planes several times a month.) According to Bureau of Transportation Statistics survey data, only about 40% of the population had taken even one trip by commercial aircraft in the previous 12 months.

For this poll to really have meaning, the question should be asked of people who are affected and who understand what is being asked. Question wording has a huge impact on results. Most journalists don’t bother to look at what was actually asked before making assumptions about what the results say.

CBS might want to consider this variation for their next poll:

Some airports are using enhanced screening techniques in airport security lines. Do you think 13-year-old children should or should not have their genitals touched by government agents without probable cause?

I’d bet that the results are the mirror opposite.

Update: ABC News did its own poll on TSA screening that addressed both of the issues above (wording bias and sample bias). It’s results were very different.

Specifically, ABC asked:

The Transportation Security Administration is increasing its use of so-called ‘full-body’ digital x-ray machines to screen passengers in airport security lines. (Supporters say these machines improve the ability to spot hidden weapons and explosives, and reduce the need for physical searches.) (Opponents say these machines invade privacy by producing x-ray images of a passenger’s naked body that security officials can see, and don’t provide enough added security to justify this.) Which comes closer to your own view – do you support or oppose using these scanners in airport security lines?

Among people who fly at least once a year, 58% support the machines and 37% oppose. Opposition rises among people who fly more frequently, although that sample size was small.