View Full Version : I pit z-scores (not very angry; sad)
01-06-2005, 07:12 PM
I teach at a university that summarizes student evaluations of courses by calculating z-scores across the department (students are asked questions in the format, "compared to other courses..."). This means that each instructor is functionally competing with all the others, as well as with the other classes s/he's teaching in the same term. I am in the odd and unpleasant position of receiving low evaluations on all of my courses for fall term. My actual numbers are okay to great, but because others also had good evaluations, my z-scores drop to the bottom of the heap. This wouldn't matter so much except that the college looks at the z-scores, not the actual averages in "excellent," "good," etc. or the modal student responses. I'm not in a tenure line, which means this doesn't affect tenure possibilities, but if and when our salaries are ever unfrozen, I worry that it might affect my eligibility for a raise. Since verbal student comments were generally better than I usually get, I'm puzzled by the discrepancy and, since my averages and modes are good for these courses historically, I'm frustrated that the z-score is the bottom line.
So I pit the use of z-scores, and the artificial competition between courses they create. It is a sad day. Your scorn for z-scores used in this way would cheer me up.
01-06-2005, 07:48 PM
What I find interesting is that the question is phrased in relative terms. The FCQs that my school had students do had a similar question and I always found it a bit absurd. What if all of my courses were good that semester? Why does it even matter how my other courses have been when I'm evaluating this one?
As for the normalizing of the scores that is unfortunate. It is far better for the raw data to remain available for those making the decisions. One of my stats professors was frequently involved in tenure decisions and he considered the percentage of FCQs returned to be an important factor; the truly negative ratings had already been delivered by students just not showing up.
01-06-2005, 07:53 PM
It sounds to me like you're just being graded on the curve, probably in much the same way as your students are. If everybody makes and A - or an F for that matter - it probably says more about the limitations of the test itself than the abilities of those being tested, so you shift the curve up or down to get a useful set of scores.
01-06-2005, 07:56 PM
What if all of my courses were good that semester? Why does it even matter how my other courses have been when I'm evaluating this one?Yes. I just imagine the criticism I'd get (from coworkers and students alike) if I went back to grading on a curve. I know some instructors still do so, but it seems absurd to me--why should Suzie's test score of 89 and Juan's 94 have any relation to each other except in examining the whole group's distribution to be sure it was a fair test? If the 60 other students get scores higher than Suzie's, should she fail? Surely the 89 already accomplishes it mission of letting her know how she did on the test.
01-06-2005, 08:42 PM
If the 60 other students get scores higher than Suzie's, should she fail?Well, maybe.
It could be that that by chance every single one of your students happened to be hard working and bright, and that they all deserved A's. Maybe. Or it could be that you have a normal distribution of students, but you are such an incredible teacher that even the dullards and slackers learned an A amount in your class. Maybe.
But maybe, just maybe, you have a normal set of students and you are a good but not superhuman teacher, but your test was just too damn easy. Should those who studied and worked hard get the same grade as those who slept through class and never did the reading? That's not fair.
(I've been out of school for a while, but are you telling me that it's no longer routine to grade on a curve?)
01-06-2005, 10:08 PM
Why are you being rated on how students felt about the class?
I mean that counts for something. But should flower-arranging classes really be getting better marks than duller history ones?
01-07-2005, 12:20 AM
Should those who studied and worked hard get the same grade as those who slept through class and never did the reading? That's not fair.My guess is that a student earning 89 points on an exam wasn't sleeping.
(I've been out of school for a while, but are you telling me that it's no longer routine to grade on a curve?)I haven't taught with colleagues who graded on a curve since the mid-80's. I'm sure there are still some around, but the high schools and universities I've worked for have had a strong tendency to give grades that reflect each student's performance on assignments and tests rather than putting them on a curve where grades are relative to the other students' performance.
Why are you being rated on how students felt about the class?I think that should be a part of any teacher's assessment. I'd rather that the questions be about whether students agree that they learned something from me, rather than how hard or enjoyable the class was as compared to all the other classes.;
01-07-2005, 12:22 AM
The OP describes my feelings exactly. It was the happiest day of my teaching career when I heard that they were eliminating z-scores from out evaluations.
01-07-2005, 01:58 PM
I've now asked for copies of my previous evaluations so I can see if there was a change in my performance (as inferred from student ratings) or a change in my colleagues' performance.
01-07-2005, 03:38 PM
Your scorn for z-scores used in this way would cheer me up.
z-scores suck. Why in the hell, with 25 other perfectly acceptable letters out there (51 if you count capitals, 55 if we go with Spanish - and don't even get me started on cyrillic and cuneiform) do we always settle on z-scores? What's wrong with d-scores? Or q-scores? Heck, x is an underused letter, let's have x-scores. I can not begin to tell you how much this blatanty alphaphobic z-score crap chaps my hide. Always z. Damn z, damn you to hell!
How'd I do?
01-07-2005, 05:47 PM
How'd I do?Please! I'm very wary of assigning evaluative scores at the moment!
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