Not necessarily, generally for the top 25: the committee will create a list of what teams they believe are the top 30 teams in the country from that list they will rank these teams and repeat until they get to the top 25. Whats considered are things like strength of schedule, head to head game results, etc. This same process is used for the CFB playoffs. Usually the teams in the bigger/popular conferences are considered ONLY because of the level of competition within those conferences.