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ABSITE statistics: the absolute basics
Christian Jones, MD, FACSDepartment of Surgery
Johns Hopkins School of Medicine
statsO mean: typical “average”O median: middle numberO mode: most frequent numberO normal: type of distribution, equal about a
mean, “bell curve”, mean = median = mode
termsO incidence: interval of timeO prevalence: point in time
types of studiesO cohort study: prospective, nonrandom
assignment to treatment groupO case-control study: retrospective,
nonrandom
biasesO selection bias: test groups end up being
different, e.g., volunteers vs. populationO measurement bias: aka system bias, actual
measurement is inaccurate, e.g., recall biasO exposure bias: aka treatment bias,
treatments not applied equally or as originally planned, e.g., dead patients “withdraw”
test parametersO sensitivity: how well does the test see the
disease?O specificity: how well does the test make sure
it really is the disease?O positive predictive value: if the test says yes,
how certain can you be that it’s right?O negative predictive value: if the test says no,
how certain can you be that it’s right?
copyright, etc.This document is entirely the work of Christian Jones ([email protected]) and is hereby released into the public domain, with no rights reserved.
This is version 1.1, last modified on 28 January 2016 by Christian Jones. Contact the author by email or on Twitter (@jonessurgery) for questions, comments, or concerns.
