Objective: Performance evaluation (PE) is one of the critical activities in the assessment and improvement of management systems. Performance evaluations are done with different aims and approaches. Self-Assessment (SA) is considered as one of the most important performance evaluation methods. And, learning focus is one of the strengths of SA compared to the other performance evaluation methods. Like the other PE methods, SA has some weaknesses such as human error during performance measurement. Consequently, researches have been trying to identify the human effect on the selfassessment process. Methods: To achieve the mentioned goal, the results of the sustainable excellence (H3SE) model between 121 experts of 42 Petrochemical companies have been analyzed. The role of the intervening variables in performing self-assessment tests (e. g. age, gender, educational degree, and related experience) have been investigated. Results: Result of research reveals that the mentioned variables do not have a significant intervening impact on excellence. Conclusion: Since the present research uses a biographical variable as an intervening variable, it seems that there are unknown variables that weren’ t considered. In addition because of the statistical population (Petrochemical Industries) generalizability of research finding to the other research is impossible.