1. Mark Presley Mark Presley United States says:

    First doing a study stating the results are based on marijuana users and taking it from a database of alcohol users is not right even if hey had a dual presence in their system.  No statements about normalizing for any data. Nothing states how the study ruled out that drug use was a result of not achieving for other reasons.  In fact no link to the actual source here.  Poor irresponsible work.

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