- Thread starter Roundtoit
- Start date
- Tags standard deviation variance

As hslmith notes using confidence intervals the way you intended only works with normally distributed data. An assumption of many methods used in these is normality. So you would note that the CI are not accurate because the normality assumption was not met I believe [although with large sample sizes this might not be true as the assumption of normality is pretty robust to violations with large sample sizes I think].

First, its impossible for the standard deviation to be greater than the variance because the standard deviation is the square of the variance

If the standard deviation is 4 then the variance is 16, thus larger.

But if the standard deviation is 0.7 then the variance is 0.49, thus smaller.

And if the standard deviation is 0.5 then the variance is 0.25, thus smaller.

Noetsi! You are advising complete beginners. Look at what you are writing!

As hslmith notes using confidence intervals the way you intended only works with normally distributed data.

It would not be surprising if the Time, were the mean and standard deviation is about the same, is exponentially distributed.

SO I get my variance is essentially 12 (0 being one end of the values, 12 the other) which actually gives me a SD of 3.46 (not the 4.02 excel was giving me).