Along with the question, the respondents are asked to rate the degree to which this is happening (for example, never, sometimes, frequently, or very often) and then assign a score. These questions are meant to elicit a specific response. With the answers, doctors can arrive at some numeric value which can then be used to measure the severity of the disorder.
Some tests include physical exams, observations of behavior in different contexts, interviews with different family members, and objective time-measured tests of attention and thinking skills.
When doctors or psychologists feel it is warranted, another group of subjective questionnaires is sometimes recommended, known as the Social Skills Rating (SSR) system.