Question

DATA contains Part Quality data of three Suppliers. At α=0.05, style="color:rgb(34,34,34);">does Part Quality depend on Supplier, or should the cheapest Supplier be chosen? Part Quality Supplier Good Minor Defect Major Defect

A 100 5 8

B 160 10 4

C 150 7 11

Answer 1

H0: Null Hypothesis: Part Quality does not depend on Supplier, So, the cheapest Supplier should be chosen

HA: Alternative Hypothesis: Part Quality depends on Supplier, So, the cheapest Supplier should not be chosen (claim)

Observed Frequency:

	Good	Minor defect	Major defect	Total
Supplier A	100	5	8	113
Supplier B	160	10	4	174
Supplier C	150	7	11	168
Total	410	22	23	455

Expecteed Frequency:

	Good	Minor defect	Major defect	Total
Supplier A	410X113/455=101.82	5.46	5.71	113
Supplier B	156.79	8.41	8.80	174
Supplier C	151.38	8.12	8.49	168
Total	410	22	23	455

Test Statistic () is got as follows:

Observed (O)	Expected (E)	(O - E)2/E
100	101.82	0.03
5	5.46	0.04
8	5.71	0.92
160	156.79	0.07
10	8.41	0.30
4	8.80	2.61
150	151.38	0.01
7	8.12	0.16
11	8.49	0.74
Total = =		4.88

By Technology, p - value= 0.3002

Since p - value =0.3002 is greater than = 0.05, the difference is not significant. Fail to reject null hypothesis,

Conclusion:

Part Quality does not depend on Supplier, So, the cheapest Supplier should be chosen