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23 Cards in this Set
- Front
- Back
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Cohort Sequence (exposure and outcome)
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measurement of exposure precedes measurement of outcome
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Case-Control Sequence (exposure and outcome)
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measurement of outcome precedes measurement of exposure
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Fixed Cohort
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-same start time for all participants
-cannot enter late -not counted if leave early |
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Dynamic Population
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-can enter late
-still counted if leave early -participants can start and stop |
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Prospective (concurrent) measurement
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data collection must take place before outcome (can occur afterwards as well)
-lots of cohort studies work like this |
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Retrospective (historical/non-concurrent) measurement
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data collection takes place after outcome has occured
-most case control studies work like this (I guess, by definition, HAVE to work like this) |
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Naturalistic Sampling
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-everyone
-every n'th person |
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Purposive Sampling ("special populations")
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-over-sample one group
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Restriction Sampling
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-study just a subgroup
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Retrospective Cohort Study (aka historical cohort study)
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cohorts are identified from recorded information and the time during which they are at risk for diseased occurred before the beginning of the study!
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Prospective Cohort Study (the norm)
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exposure information is recorded at beginning of follow-up and period of time at risk for disease occurs during the conduct of the study
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Disease Incidence = RISK
Incidence is kind of code for probability here? |
q+= a / (a+b)
a-> disease+exposure a+b--> exposure in both disease and non-disease |
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Disease Incidence = Risk (mnemonic)
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once you've been exposed, what's the risk that you're going to get the disease? (probability of contracting given exposure)
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So obviously if there's a q+ (formula for risk), there's also a q-, and the formula for that would be?
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q-= c / (c+d)
c --> disease+ no exposure c+d --> disease and non-disease in the no-exposure category |
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Now that we know about q+ and q-, we can calculate relative risk
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relative risk is the ratio of the risk (incidence
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Another word for RISK?
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INCIDENCE!
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Another word for Incidence?
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RISK!
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Odds Ratio (Relative Odds) (OR)
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(a * d) / (b * c)
from (q+/1-q+)/(q-/1-q-) |
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Relative Risk (RR)
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q+/q-
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Attributable Risk (or Excess Fraction, when causality is not established)
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AR = q+ - q-
q+ = Risk of exposed q- = Risk of unexposed |
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Percent Attributable Risk (%AR)
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%AR (ex) = (q+ - q-) / q+
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Another word for Attributable Risk (e.g. when dealing with vaccine interventions)
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Efficacy (same formula, obviously)
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Population Attributable Risk
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Difference between risk in total population and risk in unexposed subjects
Pop AR = q (pop) - q- |
