Medical researcher: At the Flegco Corporation, all employees whose work involves lifting heavy objects wear back belts to prevent back injuries. ████████ █ █████ █████ ████ ██████ █████████ ███ ████ ████ █████ ███ ████████ ████ ██████ ██ ██████ ████ ████████ ████ ███ █████████ ███ ██ ███ ████ ████ ██████ ████ ████████ ████ ████ █████ ██ ███ ████ ██ ███████ ████ █████████
The author concludes that back belts don’t help prevent back injuries. This is based on the fact that in a study of Flegco employees, those who wear back belts are more likely to suffer back injuries than employees who don’t wear back belts.
The author overlooks the possibility that the people who wear back belts at Flegco start off with a higher risk of back injuries than the people who don’t wear back belts. For example, maybe the people who wear back belts are involved in manual labor, whereas the people who don’t wear back belts are office workers who don’t lift anything heavy. If this is true, then we can’t conclude that back belts don’t reduce injuries simply because the people who wear back belts have more back injuries than the people who don’t wear the belts.
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