New, effective AIDS vaccines are now being developed using the process of sieving (i.e., sifting out infections
Question:
a. Conduct a test to determine whether the vaccine is effective in treating the MN strain of HIV. Use α = .05.
b. Are the assumptions for the test, part a, satisfied? What are the consequences if the assumptions are violated?
c. In the case of a 2 Ã 2 contingency table, R. A. Fisher (1935) developed a procedure for computing the exact p-value for the test (called Fisher's exact test). The method uses the hypergeometric probability distribution (a discrete probability distribution not covered in Chapter 4). Consider the hypergeometric probability
This represents the probability that 2 out of 7 vaccinated AIDS patients test positive and 22 out of 31 unvaccinated patients test positive (i.e., the probability of the table result given the null hypothesis of independence is true). Compute this probability (called the probability of the contingency table).
d. Refer to part c. Two contingency tables (with the same marginal totals as the original table) that are more contradictory to the null hypothesis of independence than the observed table follow and are saved in the HIV2 and HIV3 files. First, explain why these tables provide more evidence to reject H0 than the original table: then compute the probability of each table using the hypergeometric formula.
GROUP * MNSTRAIN Cross tabulation
Chi-Square Tests
e. The p-value of Fisher's exact test is the probability of observing a result at least as contradictory to the null hypothesis as the observed contingency table, given the same marginal totals. Sum the probabilities of parts c and d to obtain the p-value of Fisher's exact test. (To verify your calculations, check the p-value at the bottom of the SPSS printout on the previous page.) Interpret this value in the context of the vaccine trial.
The word "distribution" has several meanings in the financial world, most of them pertaining to the payment of assets from a fund, account, or individual security to an investor or beneficiary. Retirement account distributions are among the most...
Step by Step Answer:
Statistics For Business And Economics
ISBN: 9780321826237
12th Edition
Authors: James T. McClave, P. George Benson, Terry T Sincich