Hand-washing study awash in misunderstanding …

The New York Times has reported on a study in which observers sat discreetly in bathrooms and observed whether people “properly” washed their hands (I reckon it would be quite hard to sit discreetly in a bathroom unless you’re in a cubicle). Anyway, the description of the study gave careful attention to the stats: 10.3% of women and over 15 percent of men didn’t wash at all. Of those who did wash, 22.8% did not use soap. And only 5.8% washed for more than 15 seconds.

The lead author said, “Forty-eight million people a year get sick from contaminated food, and the (American) Centre for Communicable Diseases says 50% would not have gotten sick if people had washed their hands properly. Do as your mum said: Wash your hands.”

Surely there’s some basic confusion over percentages here: 50% of those who got sick wouldn’t have if everyone had washed their hands properly, but we have no idea what percentage of those who don’t wash actually get sick.

As a matter of fact, there is no indication that these particular non-handwashers have anything to do at all with the fact that people eat contaminated food. Does it matter what bathroom activity was being carried out? Whether you use toilet paper or your foot to flush? Whether you work in food services? Whether you subsequently wash your hands before eating dinner?

Though mum may have had good advice, this sort of scare-mongering about food-borne illnesses resulting from not washing one’s hands may actually distract us from the real concerns over germs.

• Read the full analysis by Rebecca Goldin, here. She is Director of Research for STATS, an American non-profit, non-partisan service that  helps journalists think quantitatively through providing education, workshops and direct assistance with data analysis.