Tuesday, September 14, 2010

Study Reports Hand Washing Among the Public Is Increasing But the Data May Be Flawed

A new study seems to show that hand washing is on the rise nationwide and that a very high percentage of people in this country wash their hands in multiple situations. The study has two phases: a telephone survey and an observational tally of hand washing behavior in public restrooms.

If one believes the data, 96% of telephone respondents claim they always wash their hands after using a public restroom, 89% stated that they always wash after using the bathroom at home and 77% say they always wash before eating. For those observed in restrooms, 77% of over 6000 subjects washed their hands. Women were more diligent than men. The rate of hand washing has increased since the last iteration of the study in 2007.

So what are the possible problems with this study?

The telephone survey involved a carefully planned selection of all levels of society. Obviously, one had to have and answer a telephone to be included.

For the telephone survey, the results are of course self-reported. That is, the interviewer had to take the word of the respondent. Would it not be human nature to want to please the questioner and/or avoid embarrassment and answer the question “Do you always wash your hands after using a public restroom?” with a “Yes”? Proof that this is true is illustrated by the observational data, which shows a 19% lower rate of hand washing in public restrooms compared to the 96% response in the telephone survey.

For the observational component of the study, the subjects are clearly not a well-distributed cross-section of society. One must look at the venues. For reasons known only to the authors of the study, they chose [with two notable exceptions] some fairly upscale locations to observe hand washing. One venue was Atlanta’s Turner Field, home of baseball’s Braves. Ticket prices are mostly $25.00 and up and food and other prices are undoubtedly high as well. Other venues were the Chicago Museum of Science and Industry and the Chicago Aquarium. Both places are likely to attract higher socioeconomic groups. In San Francisco, they chose the Ferry Terminal Farmers Market. If one looks at the merchants in that market, one notes an artisanal cheese shop, a chocolate maker, two olive oil stores, a gelato stand and a number of other rather high-end emporia. The more proletarian [but possibly not] sites were New York City’s Grand Central and Penn Stations. On the one hand [pun intended], there are thousands of presumably employed suburbanites commuting into and out of the city daily. This group is tempered somewhat by a small but highly visible cadre of folks who live in and under these stations and [when and if they wash] wash not only their hands but a lot of other body parts in the restrooms.

Bottom line: The telephone survey results are dubious at best. Hand washing may be increasing among upper middle class and upper class urban and suburban people who frequent museums, stadiums and trendy California malls but one cannot assume that these data are applicable to the entire country.

1 comment:

Dan said...

I wash my hands multiple times a day and especially after leaving the bathroom and before meals. That being said, I am still left to wonder how it is possible for grown men in my office who walk out of the bathroom without washing their hands. It happens all the time.

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