Geographical Variation in the Prevalence of Problematic Substance Use in Canada
Canadian Journal of Psychiatry, Vol 52, No 7, July 2007 p. 427-433
http://publications.cpa-apc.org/media.php?mid=482
Scott Veldhuizen, Karen Urbanoski, John Cairney
"The pattern of large-scale differences is consistent with existing research and is probably part of a larger disparity among regions of Canada. The persistence of variation after adjustment for covariates suggests the influence of unmeasured, geographically varying factors, of which there are several candidates, including latitude and immigrant settlement patterns."
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