Final answer:
The concept that individuals evaluate their accomplishments by comparing themselves to similar individuals is based on equity theory.
Step-by-step explanation:
The concept that individuals evaluate their accomplishments by comparing themselves to similar individuals is based on Equity theory. Equity theory, developed by J. Stacy Adams in 1965, suggests that people strive for fairness and equality in their social relationships. According to equity theory, individuals compare the ratio of their inputs (effort, skills, experience) to outcomes (rewards, recognition) with the ratios of others.