Show all your work #1. Efficacy of the Varicella vaccine was tested during an ou
ID: 208338 • Letter: S
Question
Show all your work #1. Efficacy of the Varicella vaccine was tested during an outbreak of varicella (chicken pox) in a Nebraska town in 2004. Children who were vaccinated and others were monitored during their childhood and cases of chicken pox noted. Data on the number of vaccinated and not-vaccinated and those who acquired Chicken pox are given below Researchers wish to see if the vaccination program was effective or not? (10 pts) Vaccinated? No Yes Total Chicken Pox - Yes Chicken Pox-No Total 27 115 1-12 18 15 100 109 (a) Is the vaccine for Varicella effective? Calculate Relative Risk of getting Chicken Pox for this study? Interpret the RR. (b) Calculate and interpret the Odds Ratio (OR). (c) Is the OR similar to the RR? Explain why they are (or not) similar Calculate the incidence of Chicken Pox in the non-vaccinated that could have been prevented by vaccinations. (AR) (d) What is the proportion of total incidence of Chicken pox in the non-vaccinated that can be attributed to lack of Vaccination? (AR%) Explain your answer. (e)Explanation / Answer
Answer:
Based on the given information:
The 2x2 Contigency table is of the form:
The given data:
(a) Is the vaccine for Varicella effective? Calculate Relative Risk of getting Chicken pox for this study. Interpret the RR.
(b) Calculate and interpret the Odds Ratio (OR)
(c) Is the OR similar to the RR? Explain why they are (or not) similar.
Relative risk and Odds Ratio are two different measures of association and are interpreted differently. Relative risk ratio basically deals with the probability values (ratio of probability values) whereas odds ratio is ratio of odds and compare events with non events.
(d) Calculate the incidence of Chicken Pox in the non-vaccinated that could have been prevented by Vaccination. (AR) Attributable Risk
(e) What is the proportion of total incidence of Chicken Pox in the non-vaccinated that can be attributed to lack of Vaccination? (AR%). Explain your answer.
AR% = 0.5362*100 = 53.62%
Vaccinated Disease Present Disease Absent Total Risk factor present (success, Exposed) A B R1 (A+B) Risk factor absent (failure,Unexposed) C D R2 (C+D) Total C1 C2 N(A+B+C+D)