Hi John: I decided to use 3-level categorical age: children, younger adolescents, older adolescents. I also included year-age in the stratified analysis. Both year-age and categorical age significantly correlated with treatment adherence (N = 300), however when they were stratified into 3 age groups (each n is approx. 100), year-age was no longer significant. This is done by using logistic regression. So, I concluded that categorical age was better than year-age in this study. Am I right or am I too hasty to jump into conclusion. There is a possibility that I did not have enought people in each group? Thank you for your help.