austin_dern (austin_dern) wrote,

On the lonely gypsum weed

I'm still out of academia, really, apart from doing some research and getting started on that second draft of the book. However, I got to wet my toes back in the good proper stuff again. You see, my mother teaches as an adjunct a course on experimental methods, for a psychology class, and while most of that is very low-mathematics there is the need to explain significance testing and the Gaussian distribution and that sort of thing. This is ordinarily the point in the class where her students freeze up, panic, talk about things like ``dyscalcula'', and wince at how they really can't skip this without being lost for the rest of the course.

So --- and she's done this before --- she invited me in to talk about the first step of these topics, the z-score. This is a way of converting raw scores in a sample to their equivalents on a standard bell curve, and while it's incredibly easy once you're comfortable with what mean and standard deviation are (the z score for a given x is x minus the mean, divided by the standard deviation), it's building those concepts that's the hard part, as isn't it always?

Thus it was that I spent an hour and a half going from my mother's given example of calculating the mean and standard deviation --- using the scores of their just-completed exam --- and showing what would happen if you added a constant to every term (the mean changes, the standard deviation does not), or multiply everything by a constant (the mean and standard deviation are multiplied by that constant), and how you can use this to rescale everything to the same distribution. We stopped before the nominal end of class, as students started to get restless and plainly distraught, but I could've gone on all day.

Trivia: The Allied offensive which captured Baghdad in March 1917 was code-named ``Yilderim'', meaning ``lightning''. Source: The First World War, Hew Strachan.

Currently Reading: Dear George: Advice And Answers From America's Leading Expert On Everything From A To B, George Burns. It's a pretty silly bunch of short questions and answers but, hey, he had 800 years of vaudeville, radio, and TV experience to draw on so it's pretty amusing.


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