Education research: college physics midterm statistics

Cuesta College Physics 205A (college physics, algebra-based, mandatory adjunct laboratory) students students take their first midterm on kinematics, Newton's laws, and circular motion in the eight week of instruction.

The midterm consists of five multiple-choice questions, two short-answer questions, and two worked-out problems, to be completed within 80 minutes (the length of a regularly-scheduled lecture).

Grading statistics:

Cuesta College
Physics 205A fall semester 2011 sections 70854, 70855 
Exam code: midterm01w4Sh
Midterm 1 results (N = 53, max score = 75):
 0-15 :   
16-30 : ******  [low = 25]
31-45 : *********
46-60 : *******************  [mean = 52.9 +/- 13.9]
61-75 : *******************  [high = 75]

The order in which students turned in their completed midterms was recorded, beginning approximately 20 minutes after starting, to 80 minutes after starting. With a linear regression r² value of 0.0644, there is no significant correlation between the completion order c turning on the midterm and resulting score S (S = -0.2342c + 59.181).