ESS210B
Prof. Jin-Yi Yu
Example
qThere are two samples, each has six measurements of wind speed. The first sample measures a wind speed variance of 10 (m/sec)2. The second sample measures a 6 (m/sec)2 variance. Are these two variance significantly different?
q
qAnswer: (1) Selected a 95% significance level (a = 0.05)
q               (2) H0: s1 = s2
q                     H1: s1 ¹ s2
q               (3) Use F-test
q                     F = 10/6 = 1.67
q               (4) This is a two-tailed test. So choose the 0.025 significance areas.
q                     For n1 = n1 = 6-1=5, F0.975=7.15.
q               (5) Since F< F0.975, the null hypothesis can not be rejected.
q               (6) Variance from these two samples are not significantly different.