Random digit dialing samples have been shown to be more representative than population samples drawn using alternative methods such as telephone directories or electronic white pages. However, random digit dialing is not free of bias. Non-random non-response is an issue, and it has been shown that reducing the non-response rate may directly reduce non-response bias. Non-responders in random digit dialing may not have been contacted because the non-responders work multiple minimum-wage jobs. The investigators will place multiple calls and leave messages on answering machines. Random digit dialing is also subject to no-telephone bias - households without telephones are out of reach by random digit dialing, and the households without telephones probably differ in socioeconomic status than the overall population. However, for the urban, suburban, and semi-rural sub-populations within British Columbia, telephone coverage is almost universal.