Suppose Scotts Lawn Care would like to test the effectiveness of four new grass fertilizers that it has developed. Each fertilizer is applied to identical-size sections of grass, and after a period of time the sections of grass are mowed. The weight of the grass clippings are used to measure the effectiveness of the fertilizer. To control for variations in soil and ambient conditions, each fertilizer was applied to five different lawns, which can act as a blocking factor. The pounds of grass clippings for each sample are shown in the following table. These data can also be found in the Excel file fertilizer.xlsx.

Fert 1 Fert 2 Fert 3 Fert 4 Lawn 1 10 12 8 10 Lawn 2 9 13 11 11 Lawn 3 9 9 13 9 Lawn 4 7 10 9 12 Lawn 5 5 13 12 10

a. Using a randomized block ANOVA and a = 0.05, does there appear to be a difference in the effectiveness of the four fertilizers?

b. If the answer to part a is no, what additional steps should be taken to test the difference in the population means of each fertilizer?

c. If warranted, determine which pairs of fertilizers were different using a = 0.05.

d. Verify your results with Excel.

AppendixLO1