Question

The company has three different processes to make the batteries.   An experiment to determine the best process has been generated for the three processes. You are the quality engineer and must determine is one process is statically better than the other processes. You have selected 5 batteries from each process and they have been tested for the hours they “hold a charge.” The results of the hours are in the following table.

Battery Manufacturing Processes

Process A	Process B	Process C
8.4	8.8	8
8.1	7.8	7
8.3	8.9	7.5
6.8	8	6.9
8.3	8.8	8

Average

7.98

8.46

7.48

1. At first glance, which process seems to be the best?

Run the Excel tool ANOVA: Single Factor analysis.

2. Based on this output, can you state at the alpha of .05 that there is a difference in the average hours of the three processes?

3. What do you base this conclusion?

Answer 1

Que.1

Process B seems to be the best because batteries made by process B hold charge for on an average 8.45 hours which is more than batteries produced by remaining processes.

Que.2

Step.1 Enter data in excel.

Step.2 Go to 'Data' menu ---> 'Data Analysis' ----> New window will pop up on screen.

Step.3 Select 'ANOVA: Single Factor' ----> Another window will pop up on screen -----> Give input and output range and press Enter. You will get following result.

Process A	Process B	Process C		Anova: Single Factor
8.4	8.8	8
8.1	7.8	7		SUMMARY
8.3	8.9	7.5		Groups	Count	Sum	Average	Variance
6.8	8	6.9		Process A	5	39.9	7.98	0.447
8.3	8.8	8		Process B	5	42.3	8.46	0.268
				Process C	5	37.4	7.48	0.277
				ANOVA
				Source of Variation	SS	df	MS	F	P-value	F crit
				Between Groups	2.401333	2	1.200667	3.631048	0.058461	3.885294
				Within Groups	3.968	12	0.330667
				Total	6.369333	14

Que.3

Since p-value for F test is 0.05846 which is slightly greater than alpha = 0.05, we accept null hypothesis and conclude that all batteries have same capacity of holding charge.