- #1
FallenApple
- 566
- 61
Say for example I want to see the rate of injury for firefighter vs police vs soldier.
##InjuryCount_{i}## The number of injuries recorded for the ith person over time
##T_{i} ## Time the person was followed. Varies from person to person.
##I(f)_{i}## indicator for ith person of being a firefighter or not, police is baseline
##I(s)_{i}## indicator for the ith person of being a soldier or not, police is baseline
Then I would model ##log(InjuryCount_{i}/T_{i})=\beta_{0} +\beta_{1}I(f)_{i}+\beta_{2}I(s)_{i}. ##
Where the regression model is either a poisson, negative binomial, or quasi poisson.
Now how would I intepret the coefficients?
Is ##exp(\beta{0} )## the estimated rate of injury for the baseline group. Or is it the estimated mean rate for the baseline group. I'm not sure which.
If we look at individuals, then I can say that it is the estimated rate of injury for someone belonging in the baseline group.
But if I look at the group, I can say that it is the estimated mean rate for the baseline group as a whole.
Not sure which one is right.
##InjuryCount_{i}## The number of injuries recorded for the ith person over time
##T_{i} ## Time the person was followed. Varies from person to person.
##I(f)_{i}## indicator for ith person of being a firefighter or not, police is baseline
##I(s)_{i}## indicator for the ith person of being a soldier or not, police is baseline
Then I would model ##log(InjuryCount_{i}/T_{i})=\beta_{0} +\beta_{1}I(f)_{i}+\beta_{2}I(s)_{i}. ##
Where the regression model is either a poisson, negative binomial, or quasi poisson.
Now how would I intepret the coefficients?
Is ##exp(\beta{0} )## the estimated rate of injury for the baseline group. Or is it the estimated mean rate for the baseline group. I'm not sure which.
If we look at individuals, then I can say that it is the estimated rate of injury for someone belonging in the baseline group.
But if I look at the group, I can say that it is the estimated mean rate for the baseline group as a whole.
Not sure which one is right.