Petition Letter
Dear Associate Dean (Academic),
I am requesting a formal review of the grading of Problem 2 on In-Class Test 2 in MATH 337, following the instructor’s decision on my informal grade review.
I understand that some deduction may be justified in part (a), since my description of the model as M/M/1 was imprecise. However, I believe that the grading did not appropriately credit the substantial correct mathematical work shown in part (b).
In part (b), I derived the stationary distribution using the birth-death balance equations, obtained its explicit form, and used it to compute the long-run average number of jobs in the system. In my view, this work also established the conclusion in part (a), because deriving a normalizable stationary distribution already shows that the system is stable. My solution therefore went beyond a bare statement of stability and carried out the full mathematical derivation.
During the informal review, the instructor explained orally that the mark on Problem 2 would remain unchanged. As I understood the explanation, the deduction was based on the fact that I did not correctly justify in part (a) that the system is stable, and that in part (b) I did not explicitly define or describe stability.
After comparing my work with the posted solution for Problem 2, which I have attached for reference, I believe that I completed the essential mathematical steps expected in the solution. For that reason, while I understand that some deduction for imprecise terminology or presentation may be reasonable, I believe that the overall mark awarded on this problem does not fairly reflect the amount of correct work shown.
The grounds for this request are:
(1) discrepancy in marking; and
(2) that the decision on the informal review was not reasonable because substantial correct work in part (b) appears to have been under-credited.
I have attached the marked work, a clean copy of the work, the course syllabus, the exam date and type, and the posted solution.
Thank you for your consideration. I respectfully request that the grading of Problem 2 be reconsidered, particularly with respect to the credit awarded for the derivation in part (b).
Sincerely,
Yixin Ma
Student Number: 20380926
I am requesting a formal review of the grading of Problem 2 on In-Class Test 2 in MATH 337, following the instructor’s decision on my informal grade review.
I understand that some deduction may be justified in part (a), since my description of the model as M/M/1 was imprecise. However, I believe that the grading did not appropriately credit the substantial correct mathematical work shown in part (b).
In part (b), I derived the stationary distribution using the birth-death balance equations, obtained its explicit form, and used it to compute the long-run average number of jobs in the system. In my view, this work also established the conclusion in part (a), because deriving a normalizable stationary distribution already shows that the system is stable. My solution therefore went beyond a bare statement of stability and carried out the full mathematical derivation.
During the informal review, the instructor explained orally that the mark on Problem 2 would remain unchanged. As I understood the explanation, the deduction was based on the fact that I did not correctly justify in part (a) that the system is stable, and that in part (b) I did not explicitly define or describe stability.
After comparing my work with the posted solution for Problem 2, which I have attached for reference, I believe that I completed the essential mathematical steps expected in the solution. For that reason, while I understand that some deduction for imprecise terminology or presentation may be reasonable, I believe that the overall mark awarded on this problem does not fairly reflect the amount of correct work shown.
The grounds for this request are:
(1) discrepancy in marking; and
(2) that the decision on the informal review was not reasonable because substantial correct work in part (b) appears to have been under-credited.
I have attached the marked work, a clean copy of the work, the course syllabus, the exam date and type, and the posted solution.
Thank you for your consideration. I respectfully request that the grading of Problem 2 be reconsidered, particularly with respect to the credit awarded for the derivation in part (b).
Sincerely,
Yixin Ma
Student Number: 20380926