It is impossible to predict exactly how a class/exam/grades will
finally turn out. This page is to help you understand a bit better how the
system works. If you have questions, feel free to come and talk to me and/or
to your TA.
1. How do we compute a score?
The maximum raw score on the midterm was 44. However, we know
that at the extremes of a distribution, values can be a bit random.
There is no real difference between a student who gets 38 and one
who gets 42: both did GREAT. (There is also no real difference
between a student who gets 2 and one who gets 6, but happily there are
no such students.)
So, first, we rescale to a maximum of 38.
Now the midterm exam is worth 20% of the overall score. I find it easiest to work with a total of 10,000 points, to avoid decimals. So the midterm is 2000.
EXAMPLE: Consider
a student who scored 29 on the midterm.
This student gets 29x2000/38 = 1526 points
towards their overall total.
(Or, if you prefer you can think of this as 15.26 percentage points
towards the overall 100%.)
If this student did equally well in all components of the class, he/she
would have a total of 5x1526 = 7630 points (Or a bit over 76%).
Last year, such a student would have ended up with a 3.0 grade on the course.
However, this may not be realistic. Very few students get the same
percent of points on all components of the class.
2. Note the overall score on the course is converted to a grade
``on a curve''.
So, it is how you do relative to the class that also
helps you to interpret your score.
Consider this same hypothetical student who scored 29 on this year's midterm. This student's midterm score is just about at the median for the class. If this student were at the median on the overall score for the class, then again likely this student would get a 3.0 grade.
3. Why do we keep class grade percentiles (approximately) constant?
Stat220 is offered to about 650 students every year; about 180 students each Fall,Winter,Spring, and fewer in the Summer. You are a large population. We (the instructors, TAs, and graders) are a small population. So, as we learn in class, there is more variation in us than in you. As a large population, the percentages at each level stabilize-- LAW OF AVERAGES!!
The highest scoring students will get a 4.0 grade: this is guaranteed.
The median grade overall will likely be 3.0: this is not guaranteed, but
it will be close to 3.0.
Typically 50% of the total overall class points will get a 2.0 grade,
but this is a guideline, not a guarantee.