The American Psychological Association emailed us to say that the correction they issued on Thursday was incorrect. The email says in part:It is unusual to make such a big deal out of an obscure statistical test, and to have to correct a correction.
I am afraid that the correction we put out regarding the teen marijuana study was not accurate. We are in the process of placing this more accurate editor's note on the release on our website. ...
Although these supplemental analyses indicated that teens who engaged in frequent marijuana use had a higher probability of meeting criteria for a psychotic disorder than infrequent/nonusers by their 30s, this difference did not reach statistical significance using a two-tailed test (p=.09). ...
The group difference on psychotic disorder approached statistical significance and would have been significant if a more liberal test (i.e., one-tailed) was utilized.
Saturday, January 23, 2016
Testing for marijuana psychosis
NPR radio reports: