In: Statistics and Probability
A sporting goods manufacturing company wanted to compare the distance traveled by golf balls produced using each of four different designs. Ten balls were manufactured with each design and were brought to the local golf course for the club professional to test. The order in which the balls were hit with the same club from the first tee was randomized so that the pro did not know which type of ball was being hit. All 40 balls were hit in a short period of time, during which the environmental conditions were essentially the same. The results (distance traveled in yards) for the four designs are provided in the Excel file Golfball.
a). At the .05 level of significance, is there evidence of a difference in the mean distances traveled by the golf balls with different designs?
b). What assumptions are necessary in (a)?
Design1 | Design2 | Design3 | Design4 |
206.67 | 217.43 | 227.12 | 230.90 |
208.29 | 221.78 | 225.14 | 228.30 |
206.54 | 218.39 | 230.10 | 232.19 |
204.80 | 224.48 | 228.86 | 225.22 |
210.00 | 212.17 | 221.79 | 229.84 |
204.16 | 214.25 | 224.20 | 231.45 |
207.10 | 221.63 | 224.32 | 221.88 |
206.03 | 229.78 | 234.65 | 235.80 |
204.84 | 213.89 | 219.85 | 228.70 |
211.21 | 214.86 | 233.35 | 225.44 |
I need help how to solve in Excel !!!
from excel > menu>data > data analysis> choose anova single factor
o/p obtained is
Anova: Single Factor | ||||||
SUMMARY | ||||||
Groups | Count | Sum | Average | Variance | ||
Design1 | 10 | 2069.64 | 206.964 | 5.246427 | ||
Design2 | 10 | 2188.66 | 218.866 | 30.66718 | ||
Design3 | 10 | 2269.38 | 226.938 | 23.18213 | ||
Design4 | 10 | 2289.72 | 228.972 | 16.10697 | ||
ANOVA | ||||||
Source of Variation | SS | df | MS | F | P-value | F crit |
Between Groups | 2990.99 | 3 | 996.9966 | 53.02982 | 2.73E-13 | 2.866266 |
Within Groups | 676.8244 | 36 | 18.80068 | |||
Total | 3667.814 | 39 |
test stat = 53.03
p value = 0.000
Decision: p-value<α , reject null
hypothesis
conclusion : there is enough evidence of significance
difference among three treatments
there is evidence of a difference in the mean distances traveled by the golf balls with different designs
b) three assumptions for ANOVA analysis, namely, independence, equal variance, and normality.