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
Relative risk reduction (RRR) definition
The proportion by which the intervention reduces the event rate.
