Paper: http://jn.sfn.org/press/April-16-2014-Issue/zns01614005529.pdf http://jn.sfn.org/press/April-16-2014-Issue/zns01614005529.p... The statistical treatment

Paper: http://jn.sfn.org/press/April-16-2014-Issue/zns01614005529.pdf http://jn.sfn.org/press/April-16-2014-Issue/zns01614005529.p... The statistical treatment looks solid, good p-values and they even controlled for multiple testing with an adjusted p-value cut-off (alpha) of p < 0.0125 Funding is a bit biased: This work was supported by the National Institute on Drug Abuse (Grants 14118,026002,026104,and 027804 to H.C.B. and Grant 034093 to J.M.G.), the Office of National Drug Control Policy, Counterdrug Technology Assessment Center (Grants DABK39-03-0098 and DABK39-03-C-0098), and the National Institute of Neurological Disorders and Stroke, National Institutes of Health (Grant 052368 to A.J.B.). H.C.B. was also supported by the Warren Wright Adolescent Center at Northwestern Memorial Hospital and Northwestern University, Chicago.J.M.G. was supported by a Harvard Medical School Norman E. Zinberg Fellowship in Addiction Psychiatry Research Figure 1 has the gist, interestingly, gray matter density slightly increased with Marijuana usage. The changes weren't that extreme for the most part, but statistically significant. The L accumbens has the largest F (Table 2), indicating a larger difference in gray matter density, the other areas don't look that extreme. I guess no-one can really say what that means exactly - is it good, is it bad? Everything you do seems to change the structure of your brain in some way (like reading a novel [1]), so it's really hard to tell whether this is 'good' or 'bad'. P.S.: It's a bit annoying that Internet discussions about publications nowadays immediately just scream 'sample size!' without looking at the stats themselves. [1] http://www.theatlantic.com/education/archive/2014/01/study-reading-a-novel-changes-your-brain/282952/ http://www.theatlantic.com/education/archive/2014/01/study-r...