Home > Chronic Diseases > Chronic Diseases and Injuries in Canada > Vol 32, No 2, March 2012 > Text Equivalent - Correlates of age at diagnosis of autism spectrum disorders in six Canadian regions
Figure 1 illustrates the process of sample selection. As shown, we excluded cases where the month and year of initial diagnosis were unknown (thus preventing us from calculating age at diagnosis) and cases where residence in the surveillance regions during the year of initial diagnosis could not be confirmed.