Question

How many tails are needed to find out if patients who took ascorbate lived longer than 548 days?

Select one:

a. One tail, because the researcher only wants to know if life expectancy increased after ascorbate treatment.

b. Either one-tail or two-tail, because both situations will tell if life expectancy changed.

c. Two-tail, because the purpose of the study was to find if life expectancy changed.

d. Either one-tail or two-tail, because both situations give the same answer.

Answer 1

a. One tail, because the researcher only wants to know if life expectancy increased after ascorbate treatment.

Hypothesis testing is run to determine whether a claim is true or not, given a population parameter. A test that is conducted to show whether the mean of the sample is significantly greater than and significantly less than the mean of a population is considered a two-tailed test. When the testing is set up to show that the sample mean would be higher or lower than the population mean, it is referred to as a one-tailed test.

In our case, we want to find out if patients who took ascorbate lived longer than 548 days (Higher than the population mean 548), therefore it is a one tailed test.