Openness, Conscientiousness, Extraversion, Agreeableness, and Neuroticism. The test is based on questionnaires used in professional research settings and is widely considered to be the most robust way to describe personality differences. The Big Five model of personality is the basis of most modern personality research and is assumed in many of the most well-regarded tests employed by psychologists who maintain close connections with academia. The test is free and can be accessed through Truity's website.