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.