Statistical Evidence. Chapter 6. What do all these numbers mean?

I have a fictional story that I tell people. It's about someone who comes to my office and says he has trouble understanding a recently published paper. I look at the title: "In vitro and in vivo assessment of Endothelin as a biomarker of iatrogenically induced alveolar hypoxia in neonates" and say that I understand why you would have trouble with a paper like this. "Yeah," he says in return, "I don't understand what this boxplot is on page 3."

You've already mastered the complex language of medicine, so don't be intimidated by technical statistical terms. I will try to provide some simple explanations of medical terms like confidence interval and odds ratio, but it's impossible to list all the possible statistical jargon.

When you do come across a statistical term that you are unfamiliar with, don't panic. Here's some general guidance.

1. Some of the statistical details are there only for the benefit of those who want to reproduce the research. Most of you recognize that you can safely skim over phrases like "reverse ion phase chromatography" so you likewise skim over phrases like "bootstrap confidence intervals using bias corrected percentiles (Efron 1982). When a statistical method is followed by a reference as in the example above, then you can take some solace in the fact that the authors do not expect you to be familiar with this method.
2. If a statistical term has several words, focus first on the one word in the term you are most familiar with (most often the noun). You may not know what "reverse ion phase chromatography" is, but you probably have a good general idea about "chromatography." Similarly, with the phrase "bootstrap confidence intervals using bias corrected percentiles" focus on the term "confidence intervals."

You do have to know some statistical terminology, of course. Anyone reading research papers should be familiar with Type I and II errors, odds ratios, survival curves, etc. A basic appreciation of simple statistical methods is enough for nine out of ten papers.

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This work is licensed under a Creative Commons Attribution 3.0 United States License. It was written by Steve Simon on 2005-05-29, edited by Steve Simon, and was last modified on 2017-06-15. Send feedback to ssimon at cmh dot edu or click on the email link at the top of the page. Category: Statistical evidence