Standard Deviation & Regression

[wewet234]

<p>Why are you guys so narrowly focused on a damn test score? It’s not just about the stupid test. You’re here doing exactly what the standardized testers want you to do. They don’t care if you learn or understand anything. That’s why we’re so conditioned to think that intellectual curiosity necessarily has to be mutually exclusive from standardized testing. </p>

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@wewet234

Students who decide to work a problem with the sole intent of doing whatever it takes just to come up with an answer are playing into the trap. The trap, the notion that bad standardized test scores mean the end of the world and the intense competition and stress that is perpetuated by this. The student cannot let a number define himself/herself. In contrast, a student who may take a little longer in the short run benefits in the long run by an intellectual exercise.
Anybody can memorize a formula. Kid X can memorize the volume of a sphere, 4/3<em>pi</em>r^3, for example. Kid Y can also do nothing but memorize. Here’s a little experiment: Tell Kid Y that the formula instead is 4/5<em>pi</em>r^3. Guess what? Kid Y will think that’s correct, simply because s/he is told that it is. Nothing further than that.
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Another example: Kid X memorized the volume formula for a sphere. Kid Y derived it. Now a question asks for the volume of a cone. Kid X doesn’t know because s/he’s stuck in a little box. Kid Y knows the technique by which one can derive an expression that gives the volume of any arbitrary figure. Who wins in the long run?

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<p>Anyway, there’s really not much I or my examples can do to change your temperament. What I can do is ask you this: </p>

<p>Suppose there are two independent random variables, A and B. The standard deviation of A is 3, and the standard deviation of is B 4. What is the standard deviation of the random variable C and D, where C = A + B, and D = A - B? Use your calculator and answer me that.</p>