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Basic standard deviation calculation

Context: Undergrad
Thread starter Graham87
Start date Dec 15, 2022
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Calculation deviation Standard Standard deviation Statistics

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2 replies · 2K views

Graham87

Thread starter
Dec 15, 2022

#1

I don’t get how they got the equation for the standard deviation. Why do they only square with the time in the denominator?

Thanks!

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gleem

Science Advisor

Education Advisor

Dec 15, 2022

#2

We know that the SD of the total number of counts n is √n and rate r =n/t

So;
n=rt
Δn = (Δr)⋅t =√(n/t)t
Δr=√(n)/t =√(n/t²)

Graham87

Dec 15, 2022

#3

gleem said:

We know that the SD of the total number of counts n is √n and rate r =n/t

So;
n=rt
Δn = (Δr)⋅t =√(n/t)t
Δr=√(n)/t =√(n/t²)

Aha! Thanks!

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