Null Hypothesis Quiz

A nutritionist wants to know if the average protein content of a popular snack bar differs from 10 grams. What is the correct null hypothesis?

The average protein content is equal to 10 grams

A psychologist compares stress scores between people who meditate and people who don't. What is the correct null hypothesis?

The average stress scores are equal for both groups.

A researcher tests whether a memory training program improves test performance by comparing average scores before and after the program. What is the correct null hypothesis?

The average test score is the same before and after training.

A wildlife biologist wants to test whether average body size differs among three frog species. What is the correct null hypothesis?

Average body size is equal across all species.

A geneticist wants to know if a population of beetles shows equal frequencies of four genotypes. What is the correct null hypothesis?

All four genotypes occur with equal frequency.

A researcher asks if political party affiliation is associated with opinion on a policy. What is the correct null hypothesis?

Policy opinion is unrelated to party affiliation.

A scientist measures temperature and metabolic rate in fish and wants to test if the two variables are linearly correlated. What is the correct null hypothesis?

There is no relationship between temperature and metabolic rate. (rho = 0)

An agronomist wants to predict crop yield based on fertilizer amount. What is the correct null hypothesis?

The slope of the regression line between fertilizer and yield is zero.

A teacher compares the average test score in her class to the school-wide average of 75%. What is the correct null hypothesis?

The average test score in her class is 75%. (mu = 75%)

A health researcher compares blood pressure between smokers and non-smokers. What is the correct null hypothesis?

The average blood pressure is equal for both groups.

A company wants to see if average productivity changes after implementing a new workflow system by comparing worker output before and after the change. What is the correct null hypothesis?

There is no difference in average productivity before and after workflow changes.

A marine biologist compares salinity tolerance among four species of algae. What is the correct null hypothesis?

Average salinity tolerance is equal across all species.

An ornithologist tests whether bird color morphs are equally represented in a population. What is the correct null hypothesis?

Each color morph is equally common.

A sociologist examines whether age group (categorical variable) is related to preference  for working remotely (prefer or don't prefer). What is the correct null hypothesis?

Remote work preference is independent of age group.

A researcher records height and arm span to test whether taller people tend to have longer arms. What is the correct null hypothesis?

There is no linear relationship between height and arm span. (rho = 0)