Question

Sample Size Sample average Sample SD

Diagnosed early bird 67 1.23 0.93
Diagnosed night owl 59 2.10 0.99

Analyze the data using a theory-based approach (use the Theory-based Inference applet) to determine whether early birds differ from night owls with respect to average nightmare frequency. The data are not strongly skewed within each group.

Express the null and alternative hypotheses for testing.

a. Null: The population average VDAS score for early birds is less than the population average VDAS score for night owls.
Alt: The population average VDAS score for early birds is greater than the population average VDAS score for night owls.

b. Null: The population average VDAS score for early birds is the same as the population average VDAS score for night owls.
Alt: The population average VDAS scores are different for the two groups.

c. Null: The population average VDAS scores are different for the two groups.
Alt: The population average VDAS score for early birds is the same as the population average VDAS score for night owls.

d. Null: The population average VDAS score for early birds is greater than the population average VDAS score for night owls.
Alt: The population average VDAS score for early birds is less than the population average VDAS score for night owls.

Answer 1

b. Null: The population average VDAS score for early birds is the same as the population average VDAS score for night owls.

Alt: The population average VDAS scores are different for the two groups.

Explanation:

Given

The above data

Required

Determine the null and alternate hypothesis

When looking out for the null hypothesis, only options with equality statements or equal sign should be selected as the null hypothesis.

i.e. statements like "equal to", "the same as", etc.

The alternate hypothesis will then contain inequalities or inequality statements

From the list of options, only option (b) is correct.