Question

The variance in a pro- duction process is an important measure of the quality of the process. A large variance often signals an opportunity for improvement in the process by Önding ways to reduce the process variance. Data showing the weight of tea bags grams for two machines were presented in Quality Progress journal (February 1995). Conduct a statistical test to determine whether there is a signiÖcant di§erence be- tween the variances in the bag weights for the two machines. Use a .05 level of signiÖcance. What is your conclusion? Which machine, if either, provides the greater opportunity for quality improvements?

Machine 1	Machine 2
2.95	3.22
3.45	3.30
3.50	3.34
3.75	3.28
3.48	3.29
3.26	3.25
3.33	3.30
3.20	3.27
3.16	3.38
3.20	3.34
3.22	3.35
3.38	3.19
3.90	3.35
3.36	3.05
3.25	3.36
3.28	3.28
3.20	3.30
3.22	3.28
2.98	3.30
3.45	3.20
3.70	3.16
3.34	3.33
3.18
3.35
3.12

Answer 1