# Uncertainty question

1. Mar 14, 2009

### hellothere123

My teacher is quite lazy and gave us a template. we are suppose to show our values and the estimates. but in the table there is a row for the standard deviations and we are suppose to put the best value +- the uncertainty. now he must have copied and pasted this for all the rows. Is there a way to find the uncertainty of the standard deviation that was found for like 10 trials? I dont think he meant for us to find the uncertainty for the standard deviation, but if it can be done, how do i find it? thanks

2. Mar 15, 2009

### Redbelly98

Staff Emeritus
The uncertainty is the sample standard deviation, divided by √N. (N is the number of trials).

EDIT:
Wait, that is for the uncertainty in the measured value. Did you need that, or the uncertainty in the standard deviation itself? That one I'm not sure of.

3. Mar 15, 2009

### hellothere123

yes how do i find the uncertainty of the standard deviation itself.

it could be a mistake on the teacher's part, but i just wanted to know if finding the uncertainty for the standard deviation was possible.

4. Mar 15, 2009

### Redbelly98

Staff Emeritus
I'm pretty sure it's possible, and that the sample standard deviation follows a chi-square probability distribution. Sorry I can't help with the details.