Arsenic is a known carcinogen and poison. The standard laboratory procedures for measuring arsenic concentration (mg/L) in water are expensive. Consider the accompanying summary data and Minitab output for comparing a laboratory method to a new relatively quick and inexpensive field method (from the article "Evaluation of a New Field Measurement Method for Arsenic in Drinking Water Samples," J. of Envir. Engr., 2008: 382-388).
Two-Sample T-Test and CI

What conclusion do you draw about the two methods, and why? Interpret the given confidence interval. [One of the article's authors indicated in private communication that they were unsure why the two methods disagreed.]

Transcribed Image Text:

SampleNe StDe SE Mean 0.64 0.35 1.10 0.60 1 19.70 10.90 Estimate for difference: 8.800 95% CI for difference: (6.498, 11.102) T-Test of difference =0 (vs not =): T-value = 12 . 16 p-value =0.001 DF = 3 11102) of ditterencce i