The Myers–Briggs Type Indicator (MBTI) is an introspective self-report questionnaire with the purpose of indicating differing psychological preferences in how people perceive the world around them and make decisions.The original versions of the MBTI were constructed by two Americans, Katharine Cook Briggs and her daughter Isabel Briggs Myers. The MBTI is based on the conceptual theory proposed by Swiss psychiatrist Carl Jung, who had speculated that people experience the world using four principal psychological functions – sensation, intuition, feeling, and thinking – and that one of these four functions is dominant for a person most of the time. The four categories are Introversion/Extraversion, Sensing/Intuition, Thinking/Feeling, Judging/Perception. Each person is said to have one preferred quality from each category, producing 16 unique types. The Center for Applications of Psychological Type states that the MBTI is scientifically supported, but most of the research on it is done through its own journal, the Journal of Psychological Type, raising questions of bias.The MBTI was constructed for normal populations and emphasizes the value of naturally occurring differences. “The underlying assumption of the MBTI is that we all have specific preferences in the way we construe our experiences, and these preferences underlie our interests, needs, values, and motivation.”Though the MBTI resembles some psychological theories, it is commonly classified as pseudoscience, especially as it pertains to its supposed predictive abilities. The test exhibits significant scientific (psychometric) deficiencies, notably including poor validity (i.e. not measuring what it purports to measure, not having predictive power or not having items that can be generalized), poor reliability (giving different results for the same person on different occasions), measuring categories that are not independent (some dichotomous traits have been noted to correlate with each other), and not being comprehensive (due to missing neuroticism). The four scales used in the MBTI have some correlation with four of the Big Five personality traits, which are a more commonly accepted framework.