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8.01 Preliminary Renormalization of Recitation Quizzes, Fall 1998

November 20, 1998



As was mentioned in the course information sheet, in 8.01 we try to do the best we can to compensate for the fact that recitation instructors have different styles in terms of the difficulty of their quizzes and the manner in which they are graded. We therefore adjust the Recitatation Quiz grades by a process that we call ``renormalization.'' Each instructor is calibrated by comparing the Recitation Quiz grades of his/her students with their Review Quiz and Final Examination grades (which are team-graded), and the Recitation Quiz grades are corrected accordingly. The correction formula guarantees that the average of the Recitation Quiz grades for all 8.01 students will either not be changed, or will perhaps go up a little.

To give you preliminary feedback on how to interpret your own Recitation Quiz scores, we have computed preliminary renormalization numbers based on the first three Recitation Quizzes, and the first two Review Quizzes. Since significantly more quiz data will exist by the end of the term, you should bear in mind that the numbers presented here are very much subject to change.

In this document I will give you the formulas for computing your own renormalized Recitation Quiz grade, and also a set of grade cuts and a histogram so that you can see where you stand. The Recitation Quiz grade will count for 20% of your final grade in the course.

HOW TO COMPUTE YOUR GRADE:

In our effort to be as fair as possible, we are using a fairly complicated method of computing the Recitation Quiz average.
STEP 1: Computation of Raw Grade

To simulate the fact that the lowest of the 5 Recitation Quiz grades will in the end be dropped, for the preliminary calculation we dropped the lowest 3/5 of a quiz for each student who has taken all the quizzes. The dropping a fractional quiz is accomplished by weighting the lowest quiz less than the others. The implementation of this procedure was further complicated by the fact that the Mon-Wed recitations had 3 full Recitation Quizzes, while in the Tues-Thurs recitations the last quiz is to count only half.

Monday-Wednesday sections:

3 out of 5 quizzes have happened, so you should drop the lowest 3/5 of a quiz. That means that one should compute a weighted average of the three quiz scores, with the lowest quiz counting as 2/5 of a quiz. Specifically, if Q1 is the lowest quiz score and Q2 and Q3 are the two others, then the desired average is:
                     0.4*Q1 + Q2 + Q3
             <Q> =  -------------------
                           2.4
If the grades were not based on 100 as the maximum possible grade, then you should scale them so that they are based on 100.

Tuesday-Thursday sections:

2.5 out of 4.5 quizzes have happened, and in the end you will be allowed to drop one quiz of the 4.5. For the preliminary calculation, your grade was computed by dropping the 0.5 quizzes. Specifically, let Q_1/2 denote the score on the quiz that counts half, and Q1 and Q2 denote the other two scores. I am assuming that the maximum possible score is 100 for all three quizzes. If Q_1/2 is the lowest score, then just drop it, so the average is
                    Q1 + Q2
             <Q> = ----------
                       2
If Q_1/2 is not the lowest, then let Q1 denote the lowest. The desired average is
                    0.5*Q_1/2 + 0.5*Q1 + Q2
             <Q> = --------------------------
                               2

Students with excused absenses, any day of the week:

If you have any excused absences on the Recitation Quizzes, then click here to find out how to compute your raw grade.

STEP 2: Computation of Renormalized Grade

We experimented with three different methods of renormalization, but found that none of them seemed to be fair in all cases. We have therefore decided to use all three, and for each student the maximum of the three calculations will be used for the renormalized grade. For each instructor, four parameters were determined by comparing the Recitation Quiz grades and the Review Quiz grades of the instructor's students. A table of these parameters is as follows:

TABLE OF RENORMALIZATION FACTORS:

SectionsInstructor RQ MB
1Busza 1.2760.580 0.99019.2
2 & 3Burgess 0.9161.526 2.185-106.7
4 & 5Hauer 1.0370.913 1.093-3.764
6, 7, & 8Javan 0.8152.300 1.066-22.7
9, 10, & 11Joss 1.0740.833 0.79918.2
12Koster 1.0220.970 0.49740.619
12 & 14Falus 0.9391.160 1.273-26.0
15, 16, & 17Burke 0.8681.641 1.445-48.6
18 & 19Su 0.9841.046 0.8907.0
20Wiese 1.1110.774 1.1150.5
21 & 22Millar 1.0640.856 1.529-32.6
23 & 24Graham 0.9401.142 1.312-28.7
25 & 26Katz 1.2040.673 1.1036.3

Use the parameters in the above table to compute your renormalized Recitation Quiz grades by each of the following three methods, and then take the maximum of the three:

Method 1:
Renormalized Grade = R * (Raw Grade)
Method 2:
Renormalized Grade = 100 - Q*(100 - Raw Grade)
Method 3:
Renormalized Grade = M * (Raw Grade) + B

WHERE DO YOU STAND?

The average raw grade for all 8.01 students on the Recitation Quizzes was 74.1, which I think is very good. Each of the renormalization methods used is designed to preserve the average for all 8.01 students, but the ``best of three'' algorithm caused the average renormalized Recitation Quiz grade to rise to 77.1.

The passing grade for the renormalized Recitation Quiz average has been set at 60.0, and other numerical grades can be translated into letter grades according to the following chart:

NUMERICAL GRADELETTER GRADE
87.0 - 100A
74.0 - 86.9B
60.0 - 73.9C
45.0 - 59.9D
0.0 - 45.0F

A histogram of the grades is shown below:

[ Recitation Quiz Grade Histogram ]

RECOMPUTATIONS BEFORE AND AFTER THE FINAL EXAM:

When all five Recitation Quizzes have been given, the renormalizations will be recalculated based on these quizzes and the three Review Quizzes. The formula for these renormalizations will be posted on the web page, in a format very similar to this document. The grades computed at this time will be considered ``semi-final,'' meaning that your grade could go up from this point, but not down.

After the final examination, when the final data is available to compare the classes with each other, the renormalized grades will be calculated one last time. If your renormalized grade is increased by this recalculation, then the new value will be used; if not, then the value computed before the final exam will be retained.

IF YOU ARE INTERESTED:


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Last modified: Friday, November 20, 1998 11:19 am