epidemiology

When I was learning how to do word problems in elementary school, we were taught to ask ourselves a few questions after arriving at an answer. One of them was, "Does my answer make sense?" For example, if a problem asked how many apples a person can buy if he has $5 and each apple costs 50 cents and your answer is negative 17 million, something has gone horribly wrong.

Does my answer make sense? is such a great question, that every published scientific paper henceforth should be required to answer it explicitly. Perhaps we would avoid seeing papers with titles like this:

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Every student in America should be required to take a class called, "What Do We Know, and How Do We Know It?" Perhaps if we learned from an early age how we know the things we claim to know, fewer Americans would fall for ridiculous conspiracy theories.

Public health is a field that is widely misunderstood, even by science journalists. That is because epidemiology is an inexact science that is complicated by a large variability in the quality of the data it produces, as well as by its reliance on advanced statistical methods. Let's leave the latter aside and focus on the former. Which epidemiological studies are most reliable and why?

From weakest to strongest, here are the most common epidemiological study designs:

Case report. A case report is...

Mammographer at WorkA large, long-term study of the value of screening mammography for saving lives of women from breast cancer supports previous studies: there was no detectable benefit in terms of lives saved thanks to routine use of the technology. The study appeared in BMJ.

The study authors led by Dr. Anthony B. Miller of the Dalla Lana School of Public Health, University of Toronto, Canada, followed almost 90,,000 women participants in the Canadian National Breast Screening Study, aged 40 to 59,...

Diet Soda

Dr. Susan E. Swithers from the Purdue Department of Psychological Sciences and Ingestive Behavior Research Center authored a commentary entitled Artificial sweeteners produce the counterintuitive effect of inducing metabolic derangements. Her opinion piece was most often mistaken for a scientific study by sensation-seeking media. It appeared in the journal, Trends in Endocrinology and Metabolism.

Much of the media take on this...