Natural Resource BiometricsTesting differences between two samples variancesTesting the difference between two variancesThis can be tested with a variance ratio test: The largest value is placed in the numerator. This test is compared to the F distribution for a significance decision. Figure 1. Example of an F distribution illustrating the critical value for an a = 0.05, v1 = 10, v2 = 10. To evaluate the results of a test if the value from the formula above is between 0 and the critical value ( the white area under the curve) the two variance values are not significantly different at the specified a level. If the value of the formula is greater than the critical value (the red area under the curve) the two variance values are significantly different at the specified a level. For table of F critical values at the a = 0.05 level.
Also See: Chapter 9  Significance of a Difference between Two Means pages 108124 in:
Chapter 9  TwoSample Hypotheses pages 126130 in:

This work is licensed under a Creative Commons AttributionNoncommercial 3.0 United States License. Author: Dr. David R. Larsen Created: July 19, 2000 Last Updated: September 13, 2014 