Which salary survey is most accurate?

I get very conflicting results from all of the salary surveys. Salary.com, SalaryExpert.com, ComputerWorld.com, InfoWorld.com, TDWI.org, SDMagazine.com, Data Masters all are so varied in what the range is for positions. Which salary survey is most accurate?|||BoTh the accurate salary SURVEYS ARE ; 1.EXPERT.COM AS AND COMPUTER WORLD .COM ARE MOSTLY ACCURATE .