In 1954, the effectiveness of the Salk pollomyelltls vaccine was tested in a U.S
ID: 3244409 • Letter: I
Question
In 1954, the effectiveness of the Salk pollomyelltls vaccine was tested in a U.S. clinical trial. Children in the first, second, and third grades were randomized to a treatment group (receiving the Salk vaccine) or a control group (receiving a placebo). A total of 401, 974 children eventually received either the vaccine or the placebo (see table on next page). They were then followed for the non-paralytic (mild Infection). a. Which probability distribution would you apply to these data? Why? b. For each group, calculate the rates of: all polio, paralytic, and non-paralytic cases. c. would you be more likely to compute a one-sided or a two-sided 95% confidence interval to compare the two rates of total polio cases? Why? d. Based on the results in (b), does It appear that the Salk polio vaccine helped to prevent disease? Explain.Explanation / Answer
Answer:
a) The probability distribution that can be applied to this data is t distribution
b) Rates of all polio, paralytic and non-paralytic cases for each group:
For vaccine group:
Rate of Polio cases = 57/200745 = 2.839 x 10-4
Rate of paralytic polio cases = 33/200745 = 1.644 x10-4
Rate of non-paralytic polio cases = 24/200745 = 1.195 x 10-4
For placebo group:
Rate of Polio cases = 142/200745 = 7.07 x 10-4
Rate of paralytic polio cases = 115/200745 = 5.729 x 10-4
Rate of non-paralytic polio cases = 27/200745 = 1.345 x 10-4