Friday, April 3, 2009

Experimental Error

There is a phrase I come across in grading papers -- a phrase that is misunderstood and used incorrectly by undergraduates everywhere. I know this because I, too, misused this phrase to magically explain away all faults. That phrase is "Experimental Error". A faulty R squared value here, an unexpected color there, a strange vapor developing, an abysmal percent yield: All an encapsulated in a simple syllogism:

1. My experiment should do "X"
2. My experiment did not do "X"
3. Therefore, experimental error strikes again!

I don't know why we, as undergraduates, grasp onto this phrase. Perhaps it's because it seems simple -- after all, we're introduced to science handed down to us by the hands of Newton, et al., as an algorithm for answering multiple choice questions.

This is an entirely understandable stance.

Before studying science in college, scientists worked with equations, and said strange things. Incomprehensible to myself, I accepted that they knew what they were talking about, and I would have to be content with understanding the depth of life from the perspective of a book-ish layman. After all, while they understood what they were talking about, how could they possibly know how to live? They clam up inside of labs with white coats discussing BORING subjects, unlocking the secrets of super-technology and miracle drugs. Who wants to do that?

Well, now I dream of getting into research, but that's not what I'm trying to drive at. The point I'm trying to make is: This is not what science is. If Newton had applied the above syllogism to the problems of physics, he could have, essentially, concluded anything he wanted and explained that the dastardly villain "Experimental Error" had again interrupted the proper data from corresponding to his explanations!

So, briefly, I want to clarify: Experimental Error is not a human characteristic. Usually, when using experimental error to explain results, students will mention the weighing of reagents, or spilling liquids. This generates a great mental image for me: Students, rushing about full of frenzy, jittering with the excitement of discovery, they forget how to hold containers, how to read balances and spill chemicals (usually acids, or volatile organics) on counter tops, their notebooks, themselves!!! Someone forgot to mention they were using ether, they light a bunsen burner, and the entire class ignites into a conflageration of epistimic glory!

It's not this exciting in the lab, but the mental image picks me up in the middle of a the dry task of grading.

So, if not that, as witnessed by the sallow looks of entertainment deprived Freshmen, what? What is experimental error? Well, to try a simple definition: Experimental error is error we can not control due to the nature of experimentation. Now what the fuck does that mean? What can't we control? Well, it's not something I really grasped for a long time, and I think it's a difficult concept to grasp unto itself -- but suppose you're in the market for buying your first car. Not just a junker to get you by, but actually buying a car that you'll drive for awhile. It's a big purchase, and there are a lot of options out there. So, what do you do? You read what you can on types of cars, different brands, different models, different years. You look up the Kelly Blue Book value. You check the newspaper daily. You look at dealership prices. In general, you get a feel for what is already there from people who know what they're talking about, and then you take some cars for a spin. You get a feeling for what you like, you listen to the engine, and eventually, based upon what you've read about and what you've experienced, you make a purchase. The experimental error, in this situation, would be everything you didn't know about, everything you couldn't cover, due to your position as a fresh consumer -- maybe the car you bought has bad wiring, but nothing went wrong when test driving it. Maybe there was a better deal across town on the exact same car, but you didn't see it. That isn't exactly experimental error, but it's getting at it: It's something, because you are not all knowing and can't take every measurement ever conceived of everything, you just can't help. You eventually just make a jump: It's an educated jump, based upon current knowledge and experience, but a jump none-the-less, and then you find out, later on, if you made a good jump or not.

This isn't, in the strictest sense, what the scientific method is all about. There's a lot more to it, some of which I'm still trying to comprehend. But this, a common experience in most people's lives (eventually, anyways), is closer to the scientific method than the undergraduate rationalization of experimental error -- and we're supposed to be studying this stuff!

So why, exactly, do we formulate science this way? I could raise awareness of the inadequacies of our educational system, but that's about as vague and useless as fortune cookie advice. I don't have the answer to the question, it's a question for you, the reader! to think about. I know I will be.

Also, I want to introduce myself as a new blogger: I am a chemistry undergraduate minoring in physics at a small liberal arts college. I want to make particular emphasis about that -- the undergraduate status, not the liberal arts college -- because I am in no way an authority on the subjects I want to blog about. I am fresh, new, thinking, formulating, and quite possibly wrong in all instances. But I do put forth a good amount of effort into understanding what I'm talking about before I start talking about it, so everything I write will be in good faith, at least. I work as a TA at my college for the introductory chemistry labs, and I find that if I explain what I'm learning I feel I understand what I'm learning more. I will update weekly/bi-weekly, and the subjects will include: Science! Chemistry! Physics! Philosophy of Science! Science Education! Popular Science! So tune in next week!

1 comment:

  1. thanks for writing.. i have graduated with a degree in health science and after plenty of lab reports i still find myself banging my head against the wall trying to come up with good errors to include in reports.. sometimes they are just so elusive! keep up the good work and good luck in school.