People have developed tests to measure tests. Katharine Briggs a Briggs Type Indicator(MBT) is by far the most widely used of these tests.
Katharine Briggs and Isabel Myers based it on Carl Jung's theories of personality types. The test recognizes four dimensions of personality. These dimensions are set up as opposites. One dimension of opposites is introversion and extroversion Another pair of dimensions is sensing and intuition. The other two opposed dimensions include the thinking and feeling and the judging and perceiving dimensions. For the MBTI, the meanings of extroversion and introversion are similar to the meanings Jung used. That is, extroverts focus on other people and things. Introverts focus on their own thoughts and feelings. After a person completes the MBTI, they get a rating. The rating shows which four dimensions are strongest in that person's personality.