On why ‘weeding out’ weak students is wrong
I can’t get the phrase ‘think ecology’ out of my mind. Of course, if you have worked in genetics you might think that this is not too surprising: genetics used to be known as experimental evolution. You can’t miss ecology in that. I think it was was some of Ross Anderson’s writings that put the bug in me (pun intended) on how you cannot understand computer security without looking at the ecosystem of users that the code is embedded in. You have to think ecology, and economics is a key part of this ecology. If you think economics, you are of course thinking about scarcity too.
These thoughts gradually seeped through my consciousness after a meeting yesterday, when we were discussing how you select medical students (positions on course at medical school are scarce), and the pros and cons of various selection methods. In broad brush stroke, it seems to me bureaucracies like reliability, but neglect ecology.
Well, we all know the mantra: you cannot have validity without reliability. Absolutely true. In a static world. But we do not live in a static world, but rather in an ecosystem where the agents all modify behaviours in the light of everybody else’s actions. The result is a pressure to create more and more reliable exams, which act so as to distort the learning environment more and more away from what common sense dictates. So, we have an ecosystem with lots of different species, each species representing a type of activity we value. We then select the ones that are most easily reliably assessed and artificially allow these ones to replicate the most. The students see what is going on and act accordingly. We end up with exams that act as parasites that degrade our lovely garden. We want— In George Pickering’s wonderful words— students with ‘lively minds’ to flower, but we continually uproot them to see how they are doing, leaving only the weeds. So, the metaphor of ‘weeding out the weaker students’ has got it all wrong.