Grading Explanations, Fall 2014

Participation grade

There were 11 days where I took attendance. For some reason, the September 12th day had lots of problems -- I think one of the attendance pages was lost. Thus, that day is not being counted at all -- which means there are 10 attendance days being counted. It's reasonable that somebody could miss a day for whatever reason. So the participation grade is out of 9 points, meaning everybody gets a "free" missed day. Unfortunately, if you made all 10 days, you do not get any extra credit. Note that there are 11 separate entries for the attendance, one for each day; these entries do not count directly toward your overall weighted average. Instead, they count toward your participation grade, which is what is factored in to your overall weighted average.

The number of Piazza contributions is also listed in the gradebook (don't worry about the 'max points' for that one -- I just had to enter something; the max points value for this entry is completely ignored). Like the attendance, this counts toward your participation grade. This important value is the number of contributions as reported by Piazza. This is mostly answers posted (among a few other factors), but does generally not include questions asked. Each contribution listed contributed 2 percent to your overall participation grade. While this may not seem like much, keep in mind that some students had dozens of contributions via Piazza.

Note that the Piazza contributions only added to your participation grade -- one could still receive a maximum participation grade without Piazza contributions.

Thus, the participation grade was determined by:

For example, if you attended 6 of the 10 attendance quiz days, and had 12 contributions on Piazza, then your attendance score would be 6/9 = 66.67% for the attendance quizzes, plus 24% for the Piazza contributions, to yield 90.67% (or 4.53 out of 5).

This score was displayed out of 100, and rounded to two decimal places.

Grade parts

There were 11 full-length labs. Lab 5 had the AVL tree worksheet, which counted as 4 more points. There was no lab 12. Thus, there were 33 lab parts (11 labs of 3 parts each). So the total number of points for the labs was 33*10+4 = 334. Labs counted for 40% of the final course grade.

Each midterm counted for 15% of the final course grade, even though the total number of points on each midterm was different. The final counted for 25% of the final course grade. And participation counted for 5%.

The grade breakdown (how much each part counts for the final grade) is as listed on the course syllabus (md).

Grade curves

The stated curve on the exams (and one of the labs) is listed at the bottom of the CS 2150 page.

The total curve, so far, is the sum of these values: 2.25 + 2.25 + 1.25 = 5.75 points.

Rounding

Yes, we round grades. Note that round(x) = floor(x)+0.5. So we add 0.5 points to everybody's curve to take into account rounding. Note that this means rounding is already taken care of, so if you get an 89.9999999999999999999, it's still a B+, no matter how many times you ask - you don't get to round a second time (in reality, it was an 89.49).

Course curve

The curve so far is 5.75 from the exams, and 0.5 for rouding, for a final course curve of 6.25. We rounded that up to 8. Thus, everybody got 8 points added to their average (your average being what the gradebook reports).

Grade breakdown

As stated at the beginning of the semester, each 10-point "decade" is a separate letter grade range (60-70 is a D, 70-80 is a C, etc.). The exact ranges, taking into account the course curve mentioned above, are below. Note: the following table ALREADY includes the course curve! So you take your exact average from the gradebook and see where it lies on this table. And rounding has already been taken into account (see above), so you don't get to round a second time.

Minimum course average Letter grade
50.0 D-
55.0 D
59.0 D+
62.0 C-
65.0 C
69.0 C+
72.0 B-
75.0 B
79.0 B+
82.0 A-
85.0 A
93.0 A+

Note that the A+ range and the D- range follow a slightly different pattern. The A+ range is a percentage of the class (in this case, the top 7 course averages), and thus ended up being 93.0. The D- range extends down a bit more.

Permanent record

I've enabled the (terrible) Collab gradebook tool, and imported all the grades into there where they will live for all eternity. Or at least until UVa doesn't feel like keeping them around any more...

Regrade statistics

There were 5,820 lab grades assigned throughout the semester: about 170 students times 33 lab parts is 5,610; the additional was from students who dropped or withdrew from the course. There were 191 regrades that were submitted. Of those, 73 were either regrades where no additional points were returned, or were submitted because of extensions. That means that 118 regrades were due to misgrading the first time around. That is only a 2.03% error rate.