p-value Approach

Null & Alternative Hypothesis

Significance Level Of the Test

a

a

a

Test Statistics

p-value

Table VI with d.f.=n-1

Table VI with d.f.=n-1

Table VI with

d.f.=n-1

Decision

Test
of hypothesis on mean by suing Statlets with original data

If you have been given or calculated the sample mean and sample standard deviation together with the sample size you can use the Statlets window presented below.

ACTIVITY

Some quality control experiments require destructive sampling (i.e., the test to determine whether the item is defective destroys the item) in order to measure some particular characteristics of the product. The cost of desctructive sampling often dictates small samples. Suppose a manufacturer of printers for personal computers wishes to estimate the mean number of characters printed before the printhead fails. The printer manufacturer tests n = 15 printheads and records the number of characters printed until failure for each. These 15 measurements yield a mean of 1.24 and a standard deviation of 0.19 9in millions of characters). Suppose that the competitor's printers has a mean of 1.30 (in millions) for the number of characters printed before the printhead fails.

a. Test the hypothesis that mean number of characters printed before the printhead fails for this manufacturer is different than its competitor. Use the significance level 0.05.

The output will include: Sample size, Mean, Standard deviation, a 95% confidence interval for the population mean, and the result of the test.

b. Test the hypothesis that mean number of characters printed before the printhead fails for this manufacturer is less than its competitor. Use the significance level 0.05.

The output will include: Sample size, Mean, Standard deviation, one-sided 95% confidence interval for the population mean, and the result of the test.

c. The manufacturer advertises that mean number of characters printed before the printhead fails for their printer is 1.4 (in million). What would be your response?

Note the p-value of this test and respond to the question.