Cusp catastrophe model for sudden changes in a person’s behavior

Standard research methods that employ questionnaires, surveys and statistics do not provide the complete information necessary to fully account for the factors behind a sudden behavioral change such as that of an employee abruptly resigning from his job. For this reason, the catastrophe theory and qualitative simulation are used. Since the strict and rigorous mathematical catastrophe model cannot adapt to vague, incomplete and time-varying data, a qualitative–quantitative hybrid cusp model is proposed in this study. It integrates qualitative simulation (QSIM) with fuzzy set theory to facilitate the computing process. A case study is used to explain and validate the proposed method. Results indicate that this proposed method can be used to model the person’s sudden behavioral change and to explore the trajectory and mechanism of the change.