Question 4 [9 marks] In an influenza vaccine trial carried out during an epidemic of influenza, 240 adults received a newly developed influenza vaccination and 220 adults received a placebo vaccination. Overall, 100 people subsequently contracted influenza, of whom 20 were in the Influenza vaccine group and 80 were in the Placebo vaccine group. The observed data are summarized in the table below. Contracted Influenza Type of vaccine Yes No Influenza vaccine 20 220 Placebo vaccine 80 (a) When assessing the relationship between contraction of influenza and type of vaccine, briefly comment on what would be wrong with looking only at adults who received the influenza vaccine and comparing the number who contracted influenza to the number who did not contract influenza. [1 mark] (b) State an appropriate Null and Alternative hypotheses for this trial, and the test statistic which will allow you to test the Null hypothesis. Also report the distribution of this test statistic if the Null hypothesis is 140 true. [2 marks] (c) Calculate the expected value for each cell of the 2x2 table. [2 marks] (d) Calculate the value of the appropriate teststatistic using these data and report the corresponding P- value. [2 marks] (e) What do you conclude about the relationship between type of vaccination in adults and contraction of influenza in the population? Please assume a = 0.05 for this question. [2 marks] Question 4 [9 marks] In an influenza vaccine trial carried out during an epidemic of influenza, 240 adults received a newly developed influenza vaccination and 220 adults received a placebo vaccination. Overall, 100 people subsequently contracted influenza, of whom 20 were in the Influenza vaccine group and 80 were in the Placebo vaccine group. The observed data are summarized in the table below. Contracted Influenza Type of vaccine Yes No Influenza vaccine 20 220 Placebo vaccine 80 (a) When assessing the relationship between contraction of influenza and type of vaccine, briefly comment on what would be wrong with looking only at adults who received the influenza vaccine and comparing the number who contracted influenza to the number who did not contract influenza. [1 mark] (b) State an appropriate Null and Alternative hypotheses for this trial, and the test statistic which will allow you to test the Null hypothesis. Also report the distribution of this test statistic if the Null hypothesis is 140 true. [2 marks] (c) Calculate the expected value for each cell of the 2x2 table. [2 marks] (d) Calculate the value of the appropriate teststatistic using these data and report the corresponding P- value. [2 marks] (e) What do you conclude about the relationship between type of vaccination in adults and contraction of influenza in the population? Please assume a = 0.05 for this question. [2 marks]