Question

question 16

cal studies the effects of a new vaccine and designs an experiment with two groups. group a gets the vaccine and group b gets a placebo shot.

which of the following would be the null hypothesis in cals experiment?

group b is less likely to contract the virus compared to group a.
group a is less likely to contract the virus compared to group b.
group a and group b are both less likely to contract the virus.
group a and group b are equally likely to contract the virus.

Explanation:

Define the null hypothesis

Using the Null Hypothesis knowledge point
The null hypothesis \( (H_0) \) is a statement of no effect, no difference, or no relationship between variables. In an experimental setup, it assumes that any observed difference is due to chance.

Apply to the experimental setup

Using the Null Hypothesis knowledge point
Cal's experiment compares Group A (vaccine) and Group B (placebo). The null hypothesis must state that the vaccine has no effect, meaning there is no difference in the likelihood of contracting the virus between the two groups.

Evaluate the given options

Using the Null Hypothesis knowledge point

• Option 1: Assumes a difference (Group B is less likely).
• Option 2: Assumes a difference (Group A is less likely).
• Option 3: Assumes both are less likely, which does not directly state equivalence between the groups.
• Option 4: States that Group A and Group B are equally likely to contract the virus (no difference).

Answer:

• Group B is less likely to contract the virus compared to Group A.
• Group A is less likely to contract the virus compared to Group B.
• Group A and Group B are both less likely to contract the virus.
• Group A and Group B are equally likely to contract the virus. (Correct answer)