Phosphorous is a chemical that is found in many household cleaning products. Unfortunately, phosphorous also finds its way into surface water, where it can harm fish, plants, and other wildlife. Two methods of phosphorous reduction are being studied. At a random sample of 7 locations, both methods were used and the total phosphorous reduction (mg/L) was recorded. Note: For degrees of freedom d.f. not in the Student's t table, use the closest d.f. that is smaller. In some situations, this choice of d.f. may increase the P-value a small amount and thereby produce a slightly more "conservative" answer. Site 1 2 3 4 5 6 7 Method I: 0.013 0.020 0.015 0.055 0.007 0.002 0.010 Method II: 0.014 0.045 0.017 0.039 0.017 0.001 0.013 Do these data indicate a difference (either way) in the average reduction of phosphorous between the two methods? Use α = 0.05. (Let d = Method I − Method II.) (i) What is the level of significance? What is the value of the sample test statistic? (Round your answer to three decimal places.)
Phosphorous is a chemical that is found in many household cleaning products. Unfortunately, phosphorous also finds its way into surface water, where it can harm fish, plants, and other wildlife. Two methods of phosphorous reduction are being studied. At a random sample of 7 locations, both methods were used and the total phosphorous reduction (mg/L) was recorded. Note: For degrees of freedom d.f. not in the Student's t table, use the closest d.f. that is smaller. In some situations, this choice of d.f. may increase the P-value a small amount and thereby produce a slightly more "conservative" answer.
Site | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
Method I: | 0.013 | 0.020 | 0.015 | 0.055 | 0.007 | 0.002 | 0.010 |
Method II: | 0.014 | 0.045 | 0.017 | 0.039 | 0.017 | 0.001 | 0.013 |
Do these data indicate a difference (either way) in the average reduction of phosphorous between the two methods? Use
(Let d = Method I − Method II.)
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