r:ftest
A: 175, 168, 168, 190, 156, 181, 182, 175, 174, 179 B: 120, 180, 125, 188, 130, 190, 110, 185, 112, 188 a = c(175, 168, 168, 190, 156, 181, 182, 175, 174, 179) b = c(120, 180, 125, 188, 130, 190, 110, 185, 112, 188) var.test(b,a)
F test to compare two variances data: b and a F = 14.6431, num df = 9, denom df = 9, p-value = 0.0004636 alternative hypothesis: true ratio of variances is not equal to 1 95 percent confidence interval: 3.637133 58.952936 sample estimates: ratio of variances 14.64308
We obtained p-value less than 0.05, then the two variances are not homogeneous. Indeed we can compare the value of F computed with the tabulated value of F for alpha = 0.05, degrees of freedom at numerator = 9, and degrees of freedom of denominator = 9, using the function qf(p, df.num, df.den):
qf(0.95, 9, 9) [1] 3.178893 F-computed is greater than F-tabulated, so we can reject the null hypothesis H0 of homogeneity of variances.
r/ftest.txt · Last modified: 2016/09/09 09:35 by hkimscil