Grad school ranking is one way to help you select a grad school in Canada, but it isn't your only resource; nor is it the most reliable.
How do rankings work and what do they mean?
Rankings are designed to provide an overall measure of a university's or program's quality and performance. The rankings are based on a number of factors, but not all ranking publications use the same criteria or give them the same weight.
Local: Canada's Maclean's magazine publishes and annual ranking of Canadian universities and, while mostly based on undergraduate experience, the report includes separate sections on law and medical schools with extensive graduate academic and research programs.
International: Canadian grad schools also commonly appear in international rankings of world universities, such as the Financial Times of London international rankings, US News & World Report's "World's Best Colleges," and the Academic Ranking of World Universities (ARWU) based in Shanghai, China. Some rankings simply rank universities as a whole without specifying whether they are evaluating the undergrad or grad programs. These general rankings are designed to identify the "best" graduate and undergraduate institutions according to quality and value.
Program-specific: Some program-specific grad schools (like those for business, engineering, arts and humanities, law or medicine) may have their own rankings. For example, Canadian business grad schools feature in lists of top schools in the world outside the US as ranked by US publications like BusinessWeek, Forbes and The Wall Street Journal. Some professional associations or organizations dedicated to specific areas of study also publish their own rankings of grad school programs. For instance, Social Psychology Network ranks US and Canadian clinical psychology doctoral programs.
It's important to realize that some academic institutions themselves criticize the ranking process and refuse to participate (by not providing requested data). A school not appearing on a ranking list, therefore, doesn't mean it wasn't "good enough." For an alternate perspective, look for less "official" rankings in student-based resources like online school reviews.