# Thread: Urgent, which test can I use to test this hypothesis???

1. ## Re: Urgent, which test can I use to test this hypothesis???

ok a part from the test, which plot or graph can show the variation of my results? it might be more infomative than doing hypothesis test!!

2. ## Re: Urgent, which test can I use to test this hypothesis???

ok, so you have the 50 averages, a 95% confidene interval for the variance will show you where the variance "moves". You have to how large is large for you. I meant chi-square when I said chi-square. The distribution of the sample variance is a scaled chi-square. That is how you create the 95% confidence interval. A plot to do is a simple histogram and you see the shape of the distribution of the data. Do a box-plot to also. The question is, are you interested in the variance or the mean of the measures? Try also to see the quartiles and how many obervations are -+1 s.d. from the mean, -+2s.d. from the mean and _+2.5 and 3_+ s.d. from the mean. This might be more informative.

3. ## Re: Urgent, which test can I use to test this hypothesis???

I think we are more interested in the variance. Thanks for your suggestions !! very helpful

4. ## Re: Urgent, which test can I use to test this hypothesis???

Originally Posted by Masteras
The distribution of the sample variance is a scaled chi-square.
Note that there would be quite a few assumptions that have to be true for the sample variance to be a scaled chi-square.