Levels of Evidence

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If you read (or produce) scientific literature, you are hopefully aware of and use some system to appreciate how good a particular type of study is. Most “Levels of Evidence” charts organize different types of evidence into some sort of 5 tier system, with the highest level of evidence, Level 1, being the best. Level […]

Risk, or The Game of Life?

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The ideal physician is not risk-averse but rather is a risk-mitigator. Risk is inescapable. We have to be able to understand risks in real terms and also be able to communicate those risks to patients in ways that matter. The risk-mitigator recognizes that each alternative has some risks but chooses to navigate through the risks […]

Measuring How Well A Test Works, or How To Find a Hipster

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Imagine we design a test to detect a disease. In the graph below are 500 patients. Some patients have a positive test result and also have the disease; this is a True Positive (TP). Some patients don’t have the disease but nevertheless have a positive test result; this is a False Positive (FP). Most patients do […]

Primer: How To Systematically Read A Scientific Paper

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The ability to read scientific literature critically is one of the foundational skills of physicians. The most common way (and perhaps the most wrong way) that physicians read literature is to read the abstract of the paper (and sometimes just the conclusion of the abstract of the paper) and get a “take-away” message, assuming that all […]

How Do I Diagnose Ruptured Membranes? Bayesian Statistics at its Best

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The diagnosis of ruptured membranes in pregnancy is clinically very important. Decisions about delivering a pregnancy, hospitalization, and even termination of pregnancies, often depend on being correct about this diagnosis. Understanding how to diagnose ruptured membranes is fundamental to the basic practice of obstetrics; but understanding the clinical reasoning and statistics that underlie diagnosing ruptured […]

Odds Ratios Versus Relative Risk

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Many great things have been written about the difference between Odds Ratios (OR) and Relative Risks (RR). Every medical student at some point has been taught the difference. Yet these statistical terms are confused and misused every day in both the writing of and the interpretation of literature (which we’ll talk more about at the end […]