2.3 Age as Confounder
Consider whether or not age should be considered a confounding factor on the association between education and HIV.
What possible causal diagram represents the scenario where age is a confounder?
Compare the crude and adjusted ORs. Recalling that there is no formal statistical test for confounding, is there any suggestion of confounding from the analyses below?
#--- Logistic Regression
glm(serostat ~ educat + age.group, family = binomial, data = tz) %>% logistic.display() ##
## Logistic regression predicting serostat : hiv positive vs hiv negative
##
## crude OR(95%CI) adj. OR(95%CI)
## educat: ref.=no education, preschool
## primary 0.57 (0.32,1.01) 0.77 (0.43,1.37)
## secondary 0.1 (0.02,0.44) 0.13 (0.03,0.56)
##
## age.group: 20-24 vs 14-19 6.78 (3.42,13.44) 6.56 (3.29,13.08)
##
## P(Wald's test) P(LR-test)
## educat: ref.=no education, preschool 0.001
## primary 0.38
## secondary 0.006
##
## age.group: 20-24 vs 14-19 < 0.001 < 0.001
##
## Log-likelihood = -258.0038
## No. of observations = 2762
## AIC value = 524.0077