A researcher wishes to test the effectiveness of flu vaccination. 150 people are vaccinated, 180 people...

A researcher wishes to test the effectiveness of flu vaccination. 150 people are vaccinated, 180 people are vaccinated with a placebo, and 100 people are not vaccinated. The number in each group who later caught the flu was recorded. The results are shown below.

	Vaccinated	Placebo	control
Caught the flu	8	19	21
Vaccinated Placebo	142	161	79

Use a 0.05 significance level to test the claim that the proportion of people catching the fly is the same in all 3 groups.

Expert Solution

Solution:

The null and alternative hypothesis is:

H0: The proportion of people catching the fly is the same in all 3 groups

Ha: The proportion of people catching the fly is not the same in all 3 groups.

Under the null hypothesis, the test statistic is:

The observed counts are given below:

	Vaccinated	Placebo	control	Total
Caught the flu	8	19	21	48
Vaccinated Placebo	142	161	79	382
Total	150	180	100	430

The expected counts can be calculated as:

orchestra answered 1 year ago

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