I have this question:
For each of the four interaction groups
(1) no smoking, no alcohol,
(2) smoking, no alcohol,
(3) no smoking, alcohol,
(4) smoking, alcohol
– produce plots of the estimated survival function based upon Aalen’s linear model, the Cox model fit with smoking status and alcohol use as covariates, the Cox model fit with smoking status and alcohol use as stratifying variables, and the unadjusted Kaplan-Meier estimates. Overlay the plots from the different approaches in single graphs for each of the 4 groups in different colors, i.e. you should produce 4 graphs, each with 4 estimated survival functions.
Smoke is a binary variable with 1=yes and 0=no. Alcohol is a binary variable with 1=yes and 0=no. I am struggling to get the interaction terms in this way. My output is this when I run the Aalen model with code
feed.amod <- aareg(feed.surv~smokef*alcoholf+poverty+racef):
Call: aareg(formula = feed.surv ~ smokef * alcoholf + race + poverty) n= 927 35 out of 48 unique event times used slope coef se(coef) z p Intercept 0.08770 0.001410 1.63e-04 8.610 7.02e-18 smokefsmokeNo 0.04260 0.000531 1.68e-04 3.160 1.60e-03 alcoholfalcoholNo 0.00756 0.000252 3.30e-04 0.765 4.44e-01 race 0.02980 0.000318 9.98e-05 3.190 1.42e-03 poverty -0.01300 -0.000253 1.74e-04 -1.450 1.46e-01 smokefsmokeNo:alcoholfalcoholNo 0.04170 0.000227 5.38e-04 0.421 6.74e-01 Chisq=21.32 on 5 df, p=0.000704; test weights=aalen
I am just needing help understanding how to extract the cumulative hazards for this Aalen model. From there, I am understanding that I need to use the exp(-H) to extract the estimated survival. Any help or nod in the right direction is appreciated!