A manufacturer gets parts from four suppliers (call them A, B, C, and D). A random sample of 994 parts is selected from shipments by each supplier. In the samples, Supplier A has 21 defects, Supplier B has 14 defects, Supplier C has 8 defects, and Supplier D has 17 defects. Does this suggest any difference between the quality of parts provided by these suppliers? The appropriate test is 2 ; with test statistic χ2 and df = 3 .