Four pesticides used in dormant California orchards are chlorpyrifos, diazinon, methidathion, and parathion. Environmental Science & Technology (Oct. 1993) reported the number of applications of these spray chemicals over a 6-month period in California. The data for each of three types of fruit or nut orchards are shown in the accompanying table. (Parathion has since been banned for use on deciduous fruit and nut trees.)

a. Conduct a test to determine (at α = .01) whether pesticide used depends on type of orchard. 

b. Because of the large number of pesticide applications reported, the total sample size for the test, part a, is extremely large (n = 417,679). Consequently, a ”statistically significant” result may not be “practically significant.” Perform an analysis to show the magnitude of differences in the rates of methidathion application for the three orchard types.

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PESTICIDE Fruit/Nut Trees Chemical Almonds Peaches Nectarines Chlorpyrifos 41,077 4,419 11,594 Diazinon 102,935 9,651 5,928 Methidathion 21,240 5,198 1,790 Parathion 136,064 53,384 24,417