10. Measures of Association Flashcards
Risk ratio definition
Good for ETIOLOGY Tells the magnitude or relative size of the effect. [Exposed risk/Unexposed risk]; RR of 1 = null value; RR of 1.6 associated with 60% greater risk in exposed compared to unexposed; RR 1 = increased risk of disease
Risk ratio: associated study designs
Cohort studies; RCTs
Risk difference: definition
Good for PUBLIC HEALTH and individual impact. Tells what happens to YOU when you change risk. Risk of disease in exposed group MINUS risk of disease in non-exposed group (18% - 8% = 10%)
Risk difference: associated study designs
Cohort studies; RCTs
Odds ratio: definition
The odds that an outcome will occur given a particular exposure, compared to the odds of the outcome occurring in the absence of exposure. [Odds of exposure in disease/Odds of exposure in non-disease] = [AD/BC] = OR
Odds ratio: associated study designs
Case-control
Hazard definition
chance of something harmful happening
Hazard ratio: definition
Instantaneous risk over the study time period (5 yr risk). [Ratio of the hazard of an event in one group / hazard of an event in another group]. HR =1 means risk is 1x that of the 2nd group; HR = 2 implies 2x the risk
Hazard ratio: associated study designs
RCT
Absolute risk reduction: definition
Difference (SUBTRACTION) between the EVENT RATE in the INTERVENTION group & that in the CONTROL group.
Absolute risk: associated study designs
cohort studies
Protective risk ratio
RR
harmful risk ratio
RR > 1
Cox regression model definition
Investigate relationship between an event and explanatory variables. Estimates the effect. Can provide estimate of life expectancy.
Survival analysis definition
Represents the time until a single event occurs; that event is often death.
