Question

A computer manufacturer believes that the proportion of hardware malfunctions is different in humid climates than in dry climates. To test this claim, the manufacturer takes a random sample of 400 machines sold in Florida (humid) and 400 machines sold in Arizona (dry). The manufacturer finds that 44 of the machines in Florida and 24 of the machines in Arizona had hardware malfunctions.

a. Specify the competing hypotheses to test the manufacturer's claim.

b. Calculate the value of the relevant test statistic.

c. Compute the p-value. Does the evidence support the computer manufacturer's claim at the 10% significance level?

Answer 1

The codes are :

library(rateratio.test)

rateratio.test(c(44,24),c(400,400),conf.level = 0.90)

   Exact Rate Ratio Test, assuming Poisson counts

data: c(44, 24) with time of c(400, 400), null rate ratio 1
p-value = 0.02053
alternative hypothesis: true rate ratio is not equal to 1
90 percent confidence interval:
1.177980 2.895718
sample estimates:
Rate Ratio Rate 1 Rate 2
1.833333 0.110000 0.060000