Question

Introduction to Hypothesis Testing Table

Identify whether each research scenario listed in the left column of the top of the matrix, would be a one- or two-tailed test and then justify your decision. For each research scenario in the bottom of the matrix, write what the null and alternative hypotheses would be.

Research Scenario	One-tail or two-tail test	Justification
A local dermatologist claims that 30% of mole biopsies are unnecessary. Last month at his clinic, 210 out of 634 had benign biopsy results. Is there enough evidence to reject the dermatologist’s claim?
A local dermatologist claims that more than 30% of mole biopsies are unnecessary. Last month at his clinic, 210 out of 634 had benign biopsy results. Is there enough evidence to reject the dermatologist’s claim?
A local dermatologist claims that less than 30% of mole biopsies are unnecessary. Last month at his clinic, 210 out of 634 had benign biopsy results. Is there enough evidence to reject the dermatologist’s claim?
Research Scenario	Null hypothesis:	Alternative hypothesis:
A pharmaceutical company believes their weight loss drug is more effective than any program on the market. They study two groups of people: Group A is given the drug and Group B is given a placebo. They then compare weight loss over the course of 3 months.
A college professor believes class attendance is different on sunny versus cloudy days.
Researchers hypothesize that rats fed donuts for breakfast will perform worse on a task than those fed a high-protein breakfast.

Answer 1

Research Scenario	One-tail or two-tail test	Justification
A local dermatologist claims that 30% of mole biopsies are unnecessary. Last month at his clinic, 210 out of 634 had benign biopsy results. Is there enough evidence to reject the dermatologist’s claim?	This is a two-tailed test.	Because we are checking whether the dermatologist's claim of 30% is correct or not.
A local dermatologist claims that more than 30% of mole biopsies are unnecessary. Last month at his clinic, 210 out of 634 had benign biopsy results. Is there enough evidence to reject the dermatologist’s claim?	This is a one-tailed test.	Because we are checking whether the dermatologist's claim that more than 30% is unnecessary is correct or not. This is a right-tailed test.
A local dermatologist claims that less than 30% of mole biopsies are unnecessary. Last month at his clinic, 210 out of 634 had benign biopsy results. Is there enough evidence to reject the dermatologist’s claim?	This is a one-tailed test.	Because we are checking whether the dermatologist's claim that less than 30% is unnecessary is correct or not. This is a left-tailed test.

Research Scenario	Null hypothesis:	Alternative hypothesis:
A pharmaceutical company believes their weight loss drug is more effective than any program on the market. They study two groups of people: Group A is given the drug and Group B is given a placebo. They then compare weight loss over the course of 3 months.	Mean weight loss of Group A is less than or equal to the mean weight loss of Group B.	Mean weight loss of Group A is more than the mean weight loss of Group B.
A college professor believes class attendance is different on sunny versus cloudy days.	Class attendance is the same on sunny days as cloudy days.	Class attendance is different on sunny days than cloudy days.
Researchers hypothesize that rats fed donuts for breakfast will perform worse on a task than those fed a high-protein breakfast.	Rats fed donuts for breakfast will perform as efficiently as those rats who are fed high-protein breakfast.	Rats fed donuts for breakfast will perform less efficiently than those rats who are fed high-protein breakfast.