Student response to grading incentives: evidence from college economics courses

Journal of Instructional Psychology, Sept, 2006 by Dmitriv V. Chulkov

There were several types of assignments--midterm and final exams, weekly quizzes, and homework. The grading system used was such that when a student received a low score on the weekly quiz--less than 60%--he or she had to prepare and submit homework to receive credit. Those with high quiz scores received homework credit automatically. Submission of the homework following the low quiz score was voluntary. Each homework was worth about 1 percent of total course grade and involved answering questions following the corresponding chapter in the textbook. There was no additional grading of the homework. If the student expended the effort to answer the questions, they received full credit.

Regarding the homework, there is a clear incentive structure. Students who read the book and write down the answers would receive credit equal to 1 percent of course grade for each homework submitted. There were a total of ten such opportunities during the semester, so the maximum possible credit is 10 percent of course grade, which would easily mean a difference of a full letter grade for the student. An average of 69 percent of students in the sample received at least one low quiz score, and were subject to the homework incentive. However, only 39 percent of all students actually chose to expend the effort and submit the homework.

The question to be answered in this study is whether a particular type of student is more likely to respond to the grading incentive and submit the homework. The dataset used is rich in demographic detail. In particular, it is possible to identify the gender of a student, whether the student is traditional or adult, whether the student's major is related to the course topic. Table 1 presents the descriptive statistics of the data.

Results

The first question to be answered by this study is whether the grading incentives matter for the students. Among those who scored low on the quiz and were subject to the homework incentive, 57% of the students actually chose to submit the homework to receive credit for it. This number is significant, however it is also important to understand whether the response is different among the various types of students present in the dataset. The decision to submit the homework or not is in essence binary, so the technique of Probit estimation is used to evaluate the impact of independent variables on the likelihood that a student expends the effort to prepare and submit a homework. Table 2 presents the results of the Probit estimation.

The dependent variable in the table is binary, and equal to one if the homework is submitted. The independent variables are also binary, and equal to one if the student is, respectively, female, classified as adult (nontraditional), has a major that is non-related to the course subject. A binary variable is included to control for the student's year of study--equal to one if the student is freshman or senior. Finally, binary dummy variables are included to control for the semester each student was enrolled in the course.