In: Statistics and Probability
12.14 Calculating the ANOVA F test P-value. For each of the following situations, find the degrees of freedom for the F statistic and then use R to calculate the P-value.
(a) Six groups are being compared with five observations per group. The value of the F statistic is 2.47.
(b) Four groups are being compared with 11 observations per group. The value of the F statistic is 5.03.
(c) Five groups are being compared using 65 total observations. The value of the F statistic is 3.11.
(a) Six groups are being compared with five observations per group.
k=6 and n=6*5 = 30
Degree of freedom for numerator = k - 1 = 6 -1 =5
Degree of freedom for demominator = n- k = 30 - 6 = 24
The value of the F statistic is 2.47.
pf(2.47,5,24,lower.tail=FALSE).......................using r command for p value
=0.0611
(b) Four groups are being compared with 11 observations per group.
k=4 and n=11*4 = 44
Degree of freedom for numerator = k - 1 = 3
Degree of freedom for demominator = n- k = 44-4=40
The value of the F statistic is 5.03.
pf(5.03,3,40,lower.tail=FALSE).......................using r command for p value
=0.0047
(c) Five groups are being compared using 65 total observations.
k=5 and n=65
Degree of freedom for numerator = k - 1 = 4
Degree of freedom for demominator = n- k = 65-5=60
The value of the F statistic is 3.11.
pf(3.11,4,60,lower.tail=FALSE).......................using r command for p value
=0.0216