I Think Something Is Missing

News of a study comparing marijuana users who didn't use tobacco with those who used both weeds is starting to go around the blogosphere. I noticed the researchers (at least as far as the abstract is concerned) apparently did not divide non-marijuana users into tobacco using and non-tobacco using groups. To quote from the abstract:

Participants  A total of 5263 students (2439 females) aged 16 to 20 years divided into cannabis-only smokers (n = 455), cannabis and tobacco smokers (n = 1703), and abstainers (n = 3105).

Outcome Measures  Regular tobacco and cannabis use; and personal, family, academic, and substance use characteristics.

………

Conclusions  Cannabis-only adolescents show better functioning than those who also use tobacco. Compared with abstainers, they are more socially driven and do not seem to have psychosocial problems at a higher rate.

Since most of the pot users in the study also used tobacco, it looks like the combined characteristics of both kinds of pot users was probably worse than pot abstainers in general. It might be worthwhile to check if the ability to notice problems like the above is correlated with drug use or absence of drug use.

In case anybody was wondering, I was in college during the drug experimentation era, but I was in the control group.