[R-sig-ME] When to use random slop models

[Mohd Masood]

Hi all
I am working on a research questions to see the effects of district
level variables on asthma. I am using individual level (level1)
variables are district level variables (level 2). I am using
individual level variables as control.
1) My question is do I need a random slop model in this case? or
random intercept models are appropriate.
2) If yes, then how to decide which individual level variables should
be used for random slop?

Thanks
Masood