The Exam Statistics: The Mean

With the first round of (multiple-choice) midterms over, I'm now swimming in data. I want to tell you about some of the stats I go through to assess and improve my exams. Unfortunately, I'm too late to celebrate (the first) World Statistics Day. But I don't feel too bad. At least statistics has a day. It's not like there's a "Psychology Month" or anything. Oh, look--yes there is. And I'm late for that, too. Moving on...

This installment is about the (arithmetic) mean, or, if you insist, the "average." I post the class mean of every exam because you demanded it! Really, though--what use is it to you? For classes that don't grade on the curve, you don't need to know the mean (or standard deviation) to determine your absolute standing in the class. Just take your percentage correct, and see what grade that corresponds to in the syllabus. Right?

Yes, that's important. But don't you want to know how everyone else did, too? Sure you do. "Did everyone think that exam was a killer, or just me?" We want to compare ourselves to other people. Some students even want to know what the top score was. "Did anyone get 100%?" "Am I the best in the class?"

The mean also serves another purpose, when there are multiple forms of an exam. In larger classes, multiple forms of an exam are used to discourage cheating (or at least, to make it more difficult). Typically, there is one form that has the questions arranged in order of topics (e.g., questions based on the first lecture and textbook chapter first, followed by questions on the second lecture and chapter, etc.). The other forms will have the questions in a random order. Are students who get the scrambled forms at a disadvantage? Or, put another way, is there a benefit to answering questions in a sequence that reflects the arrangement of the learning materials? If so, that wouldn't be fair, would it?

The data from every exam includes the means from each form. They are usually a little bit different. But is that difference a fluke, or is it due to the ordering of questions? Hmm, sound like a job for...statistics! The data also includes the results of an ANOVA (analysis of variance) that compares the means to each other. That is, are any differences statistically significant? The answer: No. I've never had a difference at p < 0.01 or even p < 0.05. That means any differences are small; they are due to chance.

The bottom line: It doesn't matter which form you get. Isn't science cool?

Why aren't you studying?

The Coffee

When I went to high school, it wasn't cool to drink coffee. Coffee was dark, scary, and bitter. Sure, my family would have Kaffeezeit ("coffee time") on the weekends, but I was just in it for the Kuchen.

When I started university, I drank a cup of tea with milk and sugar every single morning. Even though I had a lot of 8:00 classes (because they were good classes only offered at that time, that's why), one cup of English breakfast tea was all the caffeine I needed. Some of my friends became desperate around exam time, and dipped into the go-juice. It was hilarious to watch as the normally non-caffeine consumers' eyes got really big after having a big cuppa joe. Then, they'd study like the dickens. This proved that coffee was a dangerous, dangerous substance.

Then, I started graduate school. Sure, getting a graduate degree is pretty demanding. Maybe I'd have an extra cup of tea once in a while. But the sheer, stark terror of almost having to go into the Real World was enough stimulus for me--no coffee, thanks. Maybe just a bit more sugar.

Then, one term I was Dr. Dawson's teaching assistant. He made me come to the class (I dunno, to learn something I guess); because he was on my supervisory committee, it's not like I could say no or anything. The first day of class, I met him at his office and we went to the class together. But not before he poured himself a cup of freshly made French-pressed coffee. And then he insisted on giving me a cup. It's not like I could say no or anything. The worst thing was that the coffee was: black. As black as night. No milk, and certainly no sugar (isn't that freebasing?). After that, I brought my own mug and poured sugar into it first--milk was too conspicuous.

Now, I'm neither a connoisseur (yes, I drink instant--please forgive me), nor a coffee-hound. Usually, I get by with only one cup of coffee. But if I've had a bad sleep (which does happen), you'll see me toting a cup from one of the fine local purveyors. Not my usual mug-o-water; not tea; not vodka. I have gone over to the dark side. With lots of milk and sugar.

Why aren't you studying?

The Comics

Hey, who doesn't love comics? Not me! No, I don't not love comics. Um. Here are some of my favourite web comics.

PhD Comics is about grad.students who seem to have a problem finishing their theses. (Want to know how to drive a grad.student insane? Ask her if she's finished her thesis yet. Hee!) Even if you're not a grad.student, it's still pretty funny, poking fun at all kinds of academic matters. (This one made me LOL.) There are 3 comics per week (Mon/Wed/Fri).

xkcd isn't an abbreviation or acronym--it's just the title of a webcomic, aimed at people who have the ability to think. This rules out a lot of people who just won't "get it." Some gags require knowledge of science. Gasp! Conveniently comes out 2 times per week (Tues/Thurs).

Lab Bratz isn't just for lab ratz (er, rats). Has gags on academia, but doesn't require a degree to get the joke. Only 1 per month.

Do you have any favourite web comics? (To A.K.: Yes, I know about Salad Fingers, which is technically a cartoon. And yes, I read your blog!)

Why aren't you studying?

What I Did on my Summer Vacation (2010 version)

Went to Sylvan Lake, like last year. (Well, like every year, really.) Pros: No vehicle breakdowns this time. Cons: Smoke. *cough cough* The smoke drifting in from the forest fires in BC was so bad, it actually turned a sunny day into a cloudy one.

Next: Calgary. Yes, an Edmontonian can go to Calgary without being afraid to admit it. It's just important to leave Calgary again. The trip to the zoo was especially for my youngest daughter, so she could see real “tigas,” “elfints” and “zeebas”. Her big sister liked the playground best--no manure smell. As for me, well, I just went for the food.

I had my 25th high school reunion. It was a mindbending blast from the past, catching up with people I haven’t seen since high school. Others (like Eric in the picture), I lost touch with in the middle of undergrad years at university. Unfortunately, some old friends couldn’t make it to the get-togethers, but I was able to get in touch with them again via Facebook. (Yay, Facebook! Have you heard about it yet?)

Took my wife to the Lady Gaga concert. Had pretty lousy seats, but they were better than the ones that Calgary got. Bazinga! (Her tour didn't,um, stop in Calgary.) If you look really closely at the crappy photo I took using my crappy cell phone, you can see two blobs. One is Gaga, the other is the beautiful tongue of fire rising from her piano as she sang Speechless. Yes, I need a new cell phone.

Do I have to list all the Edmonton festivals I went to? Nah. You know all about those, right?

Beyond that, hmm, let's see: the usual collection of birthday parties, days in the park, BBQs with friends. Got an MRI on my knee. Woot! Sadly, it didn't leave me with any super powers.

And work, of course. There's always work (so, it wasn't completely a summer vacation, was it?). Instead of writing new lectures, I decided to improve the ones I've got. Although--I did come up with a new mini-lecture, by special request and...well, that's another blog entry.

Now, I've got a couple of questions: What did you do on your summer vacation?

Why aren't you studying?

The Awards: 3

The Department of Psychology's Teaching Honour Roll just came out for Winter, 2010. I'm happy to say that I (*modestly*) was placed on the Honour Roll with Distinction for all three of my courses. Woot! I also have to mention that 75% of instructors who taught in that term also got on the Honour Roll. Nice going, Department of Psychology colleagues! (But why the pic of the FIFA World Cup Trophy? Because...well, because. The World Cup is on right now. That's why.)

I also had the honour of winning two (!) of the inaugural Tolman Undergraduate Teaching Awards, or TUTAs. (Just say that out loud: toot-ahs, toot-ahs. Fun!) The two I won were:

  • “The adoption of fake accents for educational purposes” (blimey!) and
  • “Assignment most likely to results in a missing-persons report” (because of this assignment--but I've never lost a student...yet)
Why are they named for Tolman? He never studied/taught/researched at the UofA. It was the choice of the Associate Chair of the Department--she's got this quote in her email sig:
"Since all the sciences, and especially psychology, are still immersed in such tremendous realms of the uncertain and the unknown, the best that any individual scientist, especially any psychologist, can do seems to be to follow his own gleam and his own bent, however inadequate they may be. In the end, the only sure criterion is to have fun." (E. C. Tolman, 1959)
So, yeah, the "TUTAs" are tongue-in-cheek awards. But I'm still gonna frame them and hang them up somewhere. Maybe in my Awards Room. That's a good place for them. As soon as I get an Awards Room.

Finally, by popular demand, here are some selected comments from my courses in the Winter, 2010 term, followed up by the every-popular snarky responses:

Intro psych:
"[I] pay to be taught, not to read a textbook"
"Textbook reading should NOT be mandatory for exams"
(Why no love for the textbook? You rated it 4.1/5, which is not spectacular, but not bad either. Like it or not, you're going to have to read in university.)
"exam...focuses too much on [lecture] notes"
"Exam questions need to be better constructed & peer-reviewed"
(OK, I admit I do have to work on my exam questions. But peer-review? And usually, I get criticized for having too few exam questions from my lectures.)
"notes are too straight forward, you can't understand"
(Er, what? I should make them less straightforward...so they are more understandable?)

Perception:
"not very helpful out of class"
(That's right: I'm not going to explain some theory when you run into me at West Edmonton Mall.)
"Your blog was very interesting & insightful"
(Thank you. That's a very interesting and insightful comment.)
"I missed a day and could not get the notes from the missed class"
(Did you ask me? All you have to do is ask me.)
"kept the class interested and attentive"
"tedious...class was very boring"
"repetitive...maybe try new ways of presenting information"
(What if you three were all trapped in an elevator for 41 hours?)
"I had no time to read [the textbook] since other psych courses also require textbook readings"
(OK, so it's the fault of those other courses. Those darn profs, making you read textbooks. Egad.)

Advanced Perception:
"would be nice to have a real textbook"
"readings were well chosen and definitely preferable to a textbook"
(There are no appropriate textbooks for a 300-level perception course. But that's OK, because you like the readings I chose.)
"quizzes were annoying...but in the end, I was thankful for them--it engages me & forced me to read [the assigned readings]"
"[quizzes] helped solidify my understanding of the main topics &...ensured I stayed up to date with the readings! It also taught me a useful study habit."
(See? Toldja.)
"I often left the class feeling as though he was talking down to us"
"was difficult to approach and was very short with me. I find him extremely snobby and condescending"
(I don't know how I screwed that up. I apologize, and I will honestly try to adjust my tone in the future.)
"forced me to work harder and think longer about the subjects covered" [in a positive context]
(Yeah, sorry about all that work and thinking.)

Why aren't you studying?

Where are they now?

For students who have completed their degrees, it's a time of endings--and of new beginnings. It makes me think of former students who've entered the "real world". I don't hear from many, but I have kept in touch with a few. Here's what's going on with them...

Colin got his Master's degree in counseling psychology and is working toward his official accreditation (you have to do a few hundred hours of work under the supervision of an accredited counseling psychologist, then pass some tests--piece of cake, eh? :-). He didn't go into graduate school right after his undergrad, but ventured into the real world first. It can be tough to go back to school after being away, but Colin showed that it is possible. The picture here was taken at a psychology conference last year. (Yup, he's standing next to esteemed psychologist Philip Zimbardo. How cool is that?) I wrote Colin a letter of reference for graduate school. He seems to think that helped him get in, but really, it was his own abilities that did it. (I have a parallel--a person who was a graduate student at the time asked me to write some software to help her with her research. That led me into doing research as an undergraduate. Without that experience, I wouldn't have gotten into graduate school and I wouldn't be where I am today. Thanks again, Linda!)

I also keep in touch with Sherry. She was a student in the first course I taught all by myself. Despite that experience (ha!) she took more of my courses and even was even my teaching assistant for a few courses. I encouraged her to go to grad.school, and she did. She's got a Master's degree, during which she got to work with actual astronauts. Again: astronauts. How cool is that? Now she manages grants for a research group here at the UofA. She deals with budgets in the millions of dollars.

Stephanie was a standout student, from the first course of mine she suffered through (ha!). She then signed up to suffer through a few more, totally shredding the courses, and getting the top grade. (Doing that definitely gets my attention and helps me to remember you.) Later, she also worked as my TA a few times--one of the best ever! I was happy to write her a reference letter for graduate school. She also took counseling psychology--one of the most difficult academic programs to get into, period. After working outside the city for a while, she's back in Edmonton again. She gets to apply her knowledge of psychology to help actual people. How cool is that?

I hope you get to use your psychology education out in the real world someday, too. If you do, drop me a line!

Why aren't you studying?

Update 8/19/2010: Marc Roy, a former TA in Advanced Perception in the mid-90s, dropped me a line. I wrote him a letter of reference, too. He entered the Clinical Neuroscience program at Simon Fraser University, earning a Master's degree. He eventually returned to Alberta to work at the Halvar Johnson Centre for Brain Injury in Ponoka, and has recently started a private practice in Red Deer. He also taught an Environmental Psychology course at Canadian University College, which is spitting distance from where I used to live (Lacombe, Alberta). And he's got two kids. Wow, great, Marc!

The Moratorium

Perception (PSYCO 267) was the first course I ever taught all by myself. That was in Spring, 1995. I went back and dug up my lecture notes from that first course. (Word processor used: Ami Pro. Operating system used: Windows 3.1. I'm gettin' all teary-eyed. >snff<) Then I compared those numbers to the current version of my lecture notes for that course (Word processor used: Word 2007. Operating system used: Windows XP. Not teary-eyed there at all.)

Number of assigned readings:

  • 1995: 12 chapters
  • 2010: 14 chapters + 1 appendix
Number of words in lecture notes:
  • 1995: 11,958
  • 2010: 28,580
It's not easy to do a direct comparison between these numbers. For example, I'm using a different textbook now than I was back in '95. In fact, my current textbook has 459 pages, the old one had 747. But look at the difference in the amount of lecture material: it's more than doubled. How (and why) can that possibly be?

First, back in 1995, I presented my notes using an overhead projector. I remember fumbling a lot with transparencies, switching lecture notes with colour pictures and figures on separate sheets. Now, almost everything is contained in PowerPoint. That's the second reason. Using PowerPoint allows me to go a lot faster through material, partly because there's no more fumbling, just clicking. But there are two further reasons underlying my increase in speed. 1. The Internet. I distinctly remember having to pause frequently to allow students to write down my long, wordy, overly long, dense explanations and definitions--and everything else. I didn't start putting my lecture notes online until the next year. In 1995, few students had Internet access. (I also don't remember getting a single email from a student.)

2. I'm better now. Um, I mean I'm a better instructor now than I was back then--a grad.student teaching only my second course ever. I'm sure my explanations were relatively poor, and I do remember having to answer quite a few questions from students in class. I like to think that now--knowing what concepts are difficult to understand--I can provide much better and more efficient explanations.

Still, the bottom line is: There is more in my course now than ever before. You might think this is unfair, especially compared to those students who had less to learn in the 90s. Or, you might be happy that you're getting as much as possible out of a course that is loaded with lots of relevant, contemporary research and theory. I like to think it's the latter case.

There are hundreds (thousands?) of papers, posters, articles, and books published and presented on topics in psychology every year. (A $2 reward to the first person to give me a reliable estimate of how many articles were published on psychological topics in 2009). I would not be doing the best possible job if I didn't stay current in the areas I teach: human factors & ergonomics, perception, cognition, and, well, introductory psychology. Which, er, means almost all of psychology, except for personality/abnormal/clinical psychology. (I'm proud that I even have two sources from 2010 in my perception course. That's about as current as I can get.)

But here's the problem: More isn't better. I can't just keep adding and adding to each course every year. I'll just have to go keep going faster and faster to cover it all. That's not doing the best possible job either. It's stupid to include a cutting-edge study at the expense of spending time explaining some concept that is core to the course. That's why I've decided to impose a moratorium on myself. I want to improve what I've got, to make sure that what I'm trying to explain comes across clearly, to smoothly transition between topics, to simplify overly complex things and add complexity back to things I've oversimplified. I've already started doing it. If you've noticed me scribbling on my notes during class, I've discovered something that I could present better...

Why aren't you studying?

Find It