Is the sampling method biased or unbiased? Select all that apply. has been tracking presidential job approval in the United States for over 80 years.[1]Links to an external site. In their presidential approval survey, Gallup asks "Do you approve or disapprove of the way [president's name] is handling his job as president?" Recently, a random sample of 1,395 U.S. adults was selected by random-digit dialing of both landlines and cell phones, but only 256 of those selected chose to respond to the survey. Of those who responded, 48% said they approved of the way the president is handling his job