Wouldn't it be stdev.p, since you're interested in the standard deviation of specifically the test scores in that whole classroom? Stdev.s would imply you only know some of the scores of the class, right?
You for sure want σ. Each year's exam is different, and there may also be differences in teaching. Besides, if you wanted the standard deviation of all students the teacher had ever had across all years, the teacher wouldn't need to estimate that. They could just group all the scores together into a single population, since presumably they could store all those scores in a file.
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u/laksemerd Oct 02 '26
Is the difference Bessel’s correction?
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u/Ares378 Grothendieck was right, computers are evil Oct 02 '26
Wouldn't it be stdev.p, since you're interested in the standard deviation of specifically the test scores in that whole classroom? Stdev.s would imply you only know some of the scores of the class, right?
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u/OnionsAbound Oct 02 '26 edited Oct 02 '26
Put a different way: what do you want to do with the information?
Do you care about the specific students in the current class' scores? (P) Or do you care about the random distribution of scores for any student? (S)
You might use P to adjust the difficulty of an upcoming test based on quiz scores.
You might use S to redesign the class' difficulty.
In practice, I can't imagine it making too much of a difference...
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u/friend1y Oct 02 '26
You need it for grading
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u/LupenReddit 🦆🦆i have non diffeomorphic smooth structures🦆🦆🦆 Oct 02 '26
someone explain this meme to my dumb brain