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# Random Questions about S1 watch

1. - Which one is an unbiased estimator for the population variance:
(Sh^2 – [(Sh)^2]/n) / n - 1
[S(x – mean)^2] / n - 1
n / n – 1
1 / n – 1 (Sx^2 – [(Sx)^2] / n)

(where s is the sign for sum of)

- On a graphical calculator, is standard deviation xon or xon^-1

Also, can I check that you do need to learn these for S1 but I seem to have a tendency of learning things that aren’t even on the syllabus
2. (Original post by alison_141288)
-

- On a graphical calculator, is standard deviation xon or xon^-1

Also, can I check that you do need to learn these for S1 but I seem to have a tendency of learning things that aren’t even on the syllabus
standard deviation is xon^-1

which exam board are you with?
3. aqa

is sd =xon where you are using an unbiased estimator of the s.d. becuase im sure my teacher said that you sometimes had to use xon
4. hmm...anyone else know?
5. anyone?
6. For Edexcel they generally use s.d = xon

Even in questions where this isn't entirely correct (where you should use xon-1), they still accept this.
7. how about for aqa though. is the general rule that you should e xon?

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