In: Statistics and Probability
The following data are from a completely randomized design.
a. Compute the sum of squares between treatments. b. Compute the mean square between treatments. c. Compute the sum of squares due to error. d. Compute the mean square due to error (to 1 decimal). e. Set up the ANOVA table for this problem. Round all Sum of Squares to nearest whole numbers. Round all Mean Squares to one decimal place. Round F to two decimal places. Round your p-value to 4 decimal places.
f. At the level of significance, test whether the means for the three treatments are equal. Calculate the value of the test statistic (to 2 decimals). The -value is - Select your answer -less than .01between .01 and .025between .025 and .05between .05 and .10greater than .10Item 16 What is your conclusion? - Select your answer -Conclude that not all treatment means are equalDo not reject the assumption that the means for all three treatments are equalItem 17 |
Ans:
Group 1 | Group 2 | Group 3 | Total | |
Sum | 954 | 852 | 804 | 2610 |
Count | 6 | 6 | 6 | 18 |
Mean, Sum/n | 159 | 142 | 134 | |
Sum of square, Ʃ(xᵢ-x̅)² | 1550 | 516 | 784 | |
Standard deviation | 17.6068 | 10.1587 | 12.5220 |
Number of treatment, k = | 3 |
Total sample Size, N = | 18 |
df(between) = k-1 = | 2 |
df(within) = N-k = | 15 |
df(total) = N-1 = | 17 |
SS(between) = (Sum1)²/n1 + (Sum2)²/n2 + (Sum3)²/n3 - (Grand Sum)²/ N = | 1956 |
SS(within) = SS1 + SS2 + SS3 = | 2850 |
SS(total) = SS(between) + SS(within) = | 4806 |
MS(between) = SS(between)/df(between) = | 978 |
MS(within) = SS(within)/df(within) = | 190 |
F = MS(between)/MS(within) = | 5.1474 |
p-value = F.DIST.RT(5.1474, 2, 15) = | 0.0199 |
Null and Alternative Hypothesis: | |
Ho: µ1 = µ2 = µ3 | |
H1: At least one mean is different. | |
Test statistic: | |
F = | 5.1474 |
Critical value: | |
Critical value Fc = F.INV.RT(0.05, 2, 15) = | 3.6823 |
p-value: | |
p-value = F.DIST.RT(5.1474, 2, 15) = | 0.0199 |
Decision: | |
P-value < α, Reject the null hypothesis. |
a)SS(between)=1956
b)MS(between)=1956/2=978
c)SS(error)=2850
d)MS(error)=2850/15=190
e)
ANOVA | |||||
Source of Variation | SS | df | MS | F | P-value |
Between Groups | 1956 | 2 | 978 | 5.15 | 0.0199 |
Within Groups | 2850 | 15 | 190 | ||
Total | 4806 | 17 |
f)Test statistic,F=978/190=5.15
alpha=0.05
The p-value is between .01 and .025
Conclude that not all treatment means are
equal
(as p-value<0.05)