Scientists often use sophisticated statistics to communicate complex data. Such modeling is rarely applied in quantifying students’ course performance. Many studies have focused on improving teaching methods in undergraduate biology labs, but fewer are committed to improving students’ competency assessments. Since student’s grades may suggest teaching effectiveness, are grades an objective and definitive metric of student performance? Likely not. In this study, we evaluate the assessment in undergraduate upper-division biology laboratory courses and challenge the concept of final grade objectivity.