standard deviation in errorbar

Question

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[a very silly question!] How to calculate the errorbar with 2 standard deviations in this example?

x=1:10;
y=rand(10,50);
errorbar(x, mean(y,2), std(y,[],2)) % 1 standard deviation

Just multiplying std by 2 in the errorbar, right?

errorbar(x, mean(y,2), 2 * std(y,[],2))

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Answer 1

Star Strider 2021-3-3

1 个投票

Not silly at all, however it may not produce the result you want.

It might be more appropriate to calculate the errors as the standard error of the mean (S.E.M.)

:

err = 2*(std(y,[],2)/sqrt(size(y,2)));                  % 2 x Standard Error Of The Mean

then:

figure
errorbar(x, mean(y,2), err) % 2 standard errors of the mean

rather than the standard deviation of the observations themselves.

Rik 2021-3-3

You're welcome.

(I deleted my answer as it overlapped with this answer too much, and this one was better)

Star Strider 2021-3-3

@Rik — I very much appreciate your compliment!