a) Compute the grand mean and respective variances for A, B, C, or D. [ 5 marks ]

b) Complete the ONE-WAY ANOVA table, where "Treatment" refers to the four different brands of antacid. [ 9 marks ]

c) Test and conclude at 5% significance level whether there is sufficient evidence to claim that the four different brands are having the same average speed in relieving gastric problems.

My answers are:

a)
Grand mean: 27.9
Variance A: 12.67
Variance B: 82
Variance C: 8.25
Variance D: 16.67

b)
Df(Tr) = 3
Df(E) = 12
Total = 15

SS(Tr) = 288.21
SS(E) = 358.77
Total = 646.98

MS(Tr) = 96.07
MS(E) = 54.9

F = 1.75

c) Null Hypothesis: All means are equal.
Alt. Hypothesis: Not as stsed in H(null).

F alpha/2, k-1, N-k = F 0.05, 3, 12
= 3.49

Conclusion:

Since F=1.75 < Fcritical =3.49, we fail to reject Ho at 5% sig level.

There is sufficient evidence to prove that H1 is true at 5% sig level.

ie. The claim that the four different brands are having the same average speed in relieving gastric problems is not true.

I think I'll post another question tmr. For those who know how to do this question, PLEASE TAG to tell me your answers. Or else I'm gonna fail MathStats.

Your participation is greatly appreciated (:

Crys.