Measures of effect Flashcards
EER (experimental event rate) equation
a / (a+b)
a = outcome present in those exposed to intervention
a = outcome absent in those exposed to intervention
CER (control event rate) equation
c / (c+d)
c = outcome present in control group (not exposed to intervention)
d = outcome absent in control group
Absolute risk reduction (ARR) equation
CER - EER
CER = control event rate
EER = experimental event rate
Relative risk
Relative risk (RR) equation
EER / CER
Relative risk (RR) equation
EER / CER
EER = experimental event rate
CER = control event rate
Relative risk (RR) equation
EER / CER
EER = experimental event rate
CER = control event rate
= the ratio of risk in the intervention (experimental) group to the risk in the control group (a ratio of the two absolute risks)
What does a relative risk (RR) value of 1 mean
The estimated effects are the same for both interventions
Which 3 studies is RR (relative risk) used
Cohort, cross-sectional and randomised control trials (not case-control)
What does a relative risk (RR) value of 1 mean
The estimated effects are the same for both interventions
If the risk ratio is > 1 then the rate of an event is increased compared to controls.
Which 3 studies is RR (relative risk) used
Cohort, cross-sectional and randomised control trials (not case-control)
What does it mean if a RR (relative risk) is <1
The rate of an event is decreased compared to controls. The relative risk reduction should therefore be calculated
What does it mean if a RR (relative risk) is >1
What does it mean if a RR (relative risk) is >1
What does it mean if a RR (relative risk) is >1
The rate of an event is increased compared to controls. The relative risk increase should therefore be calculated if necessary
