A health scientist has collected data comparing the time in days from onset of flu-like respiratory symptoms as shown by a positive test result to a negative test result for vaccinated and unvaccinated persons. She wants to see if there is a significant difference in the time to a negative test. The data is summarized in the table below. Respond to the prompts that follow. (1 point each) 1. What statistical test would be appropriate for this scenario and would it be right-tailed, left-tailed or two-tailed? Give the rationale for your choice.

2. Calculate the standard error of the test statistic. Show the calculations.

3. Calculate the value of the test statistic. Show the calculations.

4. Look up the critical value of the test statistics using alpha .05 and state a decision based on the calculated value of the test statistic and provide a rationale for that decision.

5. Calculate the effect size using Cohen'sdand interpret that result.

Vaccinated | Unvaccinated

____________ |________________

Sample size n | 31 | 31 Mean days to negative test | 6 | 9 Sample SD (s) | 2.0 | 3.0