The questionnaire asks the subject to rate his or her probability of falling asleep on a scale of increasing probability from 0 to 3 for eight different situations that most people engage in during their daily lives, though not necessarily every day. The scores for the eight questions are added together to obtain a single number.
The survey seeks to evaluate the likelihood of the subject nodding off in response to various common scenarios that most people face daily, although not necessarily every day. The aggregate scores from all eight questions are used to calculate a single overall score.