ABOUT THE GRADING PROCESS (FALL, 2007)

 

 

Course letter grades will be determined from the top down by the overall Course Score (CS), calculated from the Normalized Test Score (NTS), the Normalized Lab Score (NLS),  the Normalized Homework Score (NHS),  and the Normalized Participation Score, (NPS), as follows:

 

 

(CS) = 0.55 (NTS) + 0.30 (NLS) + 0.10 (NHS) +0.05(NPS)

 

Here the normalized test score, NTS, is the normalized (See Normalization below) value of the adjusted test score, ATS, which in turn is equal to the sum of the normalized scores for best four of the five course test hours, comprising the two hour final exam and  the three one hour exams. (See also EXAM POLICY.) In other words, the lowest (normalized) test-hour score is dropped for every student, and the resulting sum, (labeled here ATS) is renormalized to become NTS before being included into the Course Score, CS, with the weight, 0.55, specified above.

 

 

The Laboratory Score, NLS, is computed from the adjusted raw lab score, ALS, obtained from the raw sum of the semester’s lab report grades, RLS, on the basis of “80% of the Maximum” process described below. NLS’s weight is 0.30.

 

The Homework Score, NHS, is similarly obtained from the adjusted HW score, AHW, obtained from the raw sum, RHS, of the semester’s HW scores by “80% of the Maximum” process described  below.  NHS’s weight in CS is 0.10.

 

In-class clicker quizzes related to the course material will also be given from time to time. Their grades will be totaled to yield the Raw Participation Score, RPS.  By applying the “80% of the Maximum “ process described below, this raw score, RPS, will be converted into the adjusted participation score, APS,  whence the Participation Score, NPS, is obtained by Normalization (described below), as for NLS and NHS.  NPS’s weight in CS is 0.05.

 


Course Letter Grades 

 

Students whose Course Scores lie in the top 25% will receive an A. Students whose Course Scores lie in the top 50% will receive at least a B.  The A/B break-point will be set where a gap occurs in the course scores which is large enough to distinguish the performance of the lowest-scoring A student from that of the highest-scoring B student. Therefore, in practice, more than 25% of the students will likely get A’s. Likewise the precise B/C break-point will be set by such a gap, so that in practice more than 50% of the students will receive A's and B's.

 

 

To estimate letter grade equivalents from normalized scores, note that about 50% of the population falls above the average normalized score of 70. That average of 70 is therefore near the B/C letter grade breakpoint. Furthermore, about 25% of the group falls above the normalized score of 83.6 = 70 + 13.6, which is therefore the expected A/B breakpoint.  Finally, a normalized score equal to 90 = (Avg + S.D) = (70 +20) will typically place a student in the top 1/6= 16.7% of the group, quite comfortably within the top 25% who are promised A letter grades. In practise, no letter grades are computed (apart from the Early Warning grades based only on the first exam) until the end of the course, and then they are defined entirely by the course score computed as prescribed above.

 

 

 

Course Requirements

 

 

Students who do not complete the course requirements will receive an F. Failure to complete all of the Labs and submit all of the lab reports, missing the Final Exam, and/or missing two or more hourly exams each constitutes a failure to complete the course requirements. Generally students who do complete the course requirements earn a course score sufficient for a D.  Regarding the C-D breakpoint, we shall apply a prejudice in favor of C by giving D's only to students whose course scores are separated by a gap from the smooth distribution of the rest of the class. Thus despite our prejudice for C over D, a substantial gap between your score and the low edge of the continuous part of the class distribution may be dangerous to your C.

 

 

“80% of the Maximum” is Enough

 

 

The “80% of the Maximum” process for adjusting Lab, HW, and Participation components of the Total Course Score is based on the proposition that the Lab, the Homework and the Participation Quizzes are learning experiences, which, so long as they meet a certain pre-set standard, should carry no grade penalty. We consider the achievement of “80% of the Maximum” possible total score to be “good enough”. In addition, we believe that “80% of the Maximum” is within the reach of every student who is willing to expend a reasonable effort.

 

Therefore every student who achieves 80% of the Maximum possible Homework,   Lab, or Participation score will receive the same highest (=100) Adjusted Raw HW (AHW), Adjusted Raw Lab (ARL), or adjusted Raw Participation (ARP) score. Students who achieve less than “80%of the Maximum” will receive a raw score equal to the percentage of 80% which they achieve. These raw scores will then be normalized into NHS, NLS, and NPS distributions with an Average of 70 and a standard Deviation of ±20 (just as the adjusted test scores, ATS, are normalized), to yield the Normalized Lab, Normalized HW, and Normalized Participation scores, NLS, NHS and NPS, used to compute the Course Score, CS, with the 55-30-10-5 weighting given in the CS formula given above.

 

           

 

            Be Sure to Achieve the “80% of Maximum” Level

 

 

Beware: We advise everyone to make sure that he/she achieves the highest possible Adjusted HW, Adjusted Lab, and Adjusted Participation score, not just because it guarantees them the highest normalized HW, Lab and Participation scores, but because the failure to do so may seriously damage their NHS, NLS, and NPS component scores. The reason is that the normalization of a distribution in which most of the grades lie at the same maximum value can carry the few lower-than-maximum scores to quite low values, as discussed further below. The effect is drastic, but it can be avoided with due care, and it is the flip side of the decision to treat everyone equally who meets a certain specified threshold.

 

 

 

Normalization

 

Before any two grade components are added, they shall always be Normalized so that their distribution has an average of 70 and a standard deviation of 20. Thus if a certain (e.g. your own Exam I, or your adjusted lab score, ALS) grade has a raw (i.e., un-normalized) value, R, and comes from a class-wide distribution which has an average, A, and a Standard Deviation, D, the corresponding normalized grade is:

 


N = 70 + (R-A)*(20/D).

 

 

Note that this normalization process yields a new distribution which has exactly an average 70 and a standard deviation of exactly 20. The process always leaves the rank ordering of the group unchanged: The top (or the 12th from the top) student is still the top (or the 12th from the top):  a higher value of R always yields a higher value of N. But normalization provides a fair mechanism for dropping the "lowest" of several exam scores, even when one exam may have been much more difficult (i.e., had a lower class average) than the other exams. Since  the normalized scores' distributions for all exams have, by construction, the same average (70) and the same standard deviation (20), the effects of any differences in class averages for the several exams has been removed.

 

 

 

We repeat the warning issued already above: if in the original distribution, nearly everyone has the highest possible score, as we expect to be the case for the adjusted HW, adjusted  Lab, and the adjusted Participation scores (because of the "80% is good enough" rule, which replaces all scores above 80% of the maximum possible score by the same maximum score = 100) then the few students who fail to meet the 80% threshold may find their normalized score diminished significantly by the normalization calculation. Indeed, the normalized score can sometimes even become negative, although when it does so, we shall intervene and replace the negative score by a zero. This is the flip side of the promise that if you meet the minimal 80% standard, you will earn the maximum credit for HW, Lab and/or Participation: if you do not satisfy this easily achievable threshold, the normalization process may wipe out much or all of your credit for the HW, Lab and/or Participation components of your course grade.