The Correlation of Students' Entry Level GPA, Academic Performance and the National Board Examination in All Basic Science Subjects

John Q. Zhang, MD, Ph.D.


A follow up study was conducted to further investigate if the entry-level grade point average (GPA) can be used to predict a student's academic performance in the Doctor of Chiropractic program at Sherman College or on the National Board of Chiropractic Examiners Exams (NBCE) in the basic science subjects(1,2,3,4).


Fifty-two students enrolled in Sherman College of Straight Chiropractic, who completed all basic science classes and the NBCE Part I, were selected for the study. Each student's letter grades (A, B, C, D and F) from all basic science courses in the Doctor of Chiropractic Program were converted to numeric scores (95, 87, 79, 72 and 69) to determine academic performance. Class grade scores were averaged to derive a mean score for each basic science subject. Physiology class performance included fluid, respiratory, renal, endocrine, neural and cardiovascular sections. Each student's performance on the NBCE was determined by his/her score on the exam from NBCE Part I, which was subdivided into general anatomy, spinal anatomy, physiology, biochemistry, pathology and microbiology.


The results showed that students' entry level GPA had a moderate to good correlation in all basic science subjects: general anatomy (r = 0.670), spinal anatomy (r = 0.620), physiology (r = 0.570), biochemistry (r = 0.548), pathology (r = 0.583) and microbiology (r = 0.640). In addition, an analysis of the correlation of the individual student's GPA to their overall basic science class performance showed a good correlation in the basic science subjects (r = 0.720).

The student's entry level GPA had a low to moderate correlation with the student's NBCE scores, general anatomy (r = 0.514), spinal anatomy (r = 0.521), physiology (r = 0.512), biochemistry (r = 0.552), pathology (r = 0.205) and microbiology (r = 0.292). An analysis of the correlation of the individual's GPA to their overall NBCE scores showed a moderate correlation (r = 0.515).

Class performance had a good to low correlation with students' NBCE scores: general anatomy (r = 0.760), spinal anatomy (r = 0.715), physiology (r = 0.686), biochemistry (r = 0.441), pathology (r = 0.339), and microbiology (r = 0.516). An analysis of the correlation of class performance to overall NBCE scores showed a good correlation (r = 0.774).


This study confirmed earlier findings (1) that GPA is a good predictor of students' class performance (r = 0.720) and a moderate predictor of students' NBCE scores (r = 0.515) at SCSC. This study attempted to eliminate the suspicion that the predictive value of GPA for one basic science subject might hold no true predictive value to other subjects of study in the basic science divisions. It was demonstrated here that GPA could be used to predict all basic science subjects at SCSC with some reliability. The results suggest that the use of GPA in the student selection process may have merit.


It was concluded that individual student's GPA exhibited a good correlation with the student's class performance in the doctor of chiropractic program at SCSC and a moderate correlation with the NBCE performance. In comparison, the GPA was a better predictor of class performance than it was NBCE performance. The best predictor of the NBCE scores is class performance (r = 0.774). Why GPA does not correlate well with NBCE is in need of further study.


  1. Zhang Q. and Newlin S. The correlation of student entry level GPA, class performance and the National Board Examination. J. Chiropractic Education. 1997. 11(1):19-25.
  2. Zhang Q, Moore GL. Repeatedly used known test questions reduces the students’ understanding of the materials taught in class. J. Chiropractic Education. 1997.
  3. Calkins EV, Willoughby TL. Predictors of black medical student success. Journal of the National Medical Association. 1992. 84(3):253-6.
  4. Templetion MS, Burcham A, Franck L. Predictive study of physical therapy admission variables. J Allied Health 1994. 23(2):79-87.