Standard deviation as a percentage

jolodo

New Member
Hi i'm new here and have a really quick question,
How do you interpret a standard deviation given as a percentage (in this case 20%)?
I need to use the variance in further calculations (working out type i and ii errors), the data is normally distributed, and the sample size is 30, i have further information but i'm not sure its relevant.
I'm sure the way to proceed is simple, but i'm stuck!!
Any help would be apreciated ledzep

Point Mass at Zero
You sure it was standard deviations? It is quite likely that you're given the Coefficient of Variation (CV) , which are reported as percentages.

$$CV= \frac{\sigma}{\mu}$$ where $$\sigma$$ is your standard deviation and $$\mu$$ is your mean.

jolodo

New Member
That would make more sense!! But I just checked and it definitely means standard deviation: "with population standard deviation 20%.”
Could it mean that the standard deviation is 0.2*(sample size) = 0.2*(30)? That was my first guess at what to try but I’m not sure there is any mathematical justification!!