You'll be seeing quite a lot of stories over the next few days that reference a study called, Impacts of recreational cannabis legalization on cannabis use: a longitudinal discordant twin study.
The stories will be unified in their "analysis" of the study.
Writing as one, they will declare:
Recreational cannabis use increased by 20%
As with most things, most especially research studies, the truth is usually less clear than the headlines used to launch articles into the googlesphere.
The truth is sometimes called the devil in the detail.
The most obvious demons that stood out to me in this particular study, and the quotes you won't find referenced in any of the news stories that talk about a 20% increase in consumption are these two;
One potential alternative explanation for increases in use associated with legalization could be that it instead reflects an increased openness to report activities that are no longer illegal. We cannot determine whether this is the case, but we note that we also saw increases in reported cannabis use by residents of illegal states.
I can only talk to my experience as a patient who has been prescribed legal medical cannabis, that the very first rule of cannabis club is you don't talk about cannabis club. ¯\_(ツ)_/¯
Study link: