Question

A disease has annihilating amphibian populations at high levels. Researchers has been trying to develop some treatment that can counteract the disease and save some of the amphibian populations. To test which of two potential solutions is more effective, they take a sample of frogs and randomly divide them into two groups. After being treated, 256 of the 400 frogs in group 1 ended up surviving exposure to the pathogen; 300 of the 482 frogs in the second group survived. For the following questions, calculate your difference in the order: group 1 - group 2. The standard error of the difference was 0.033.

(1) Calculate the test statistic:

(2) Find the p-value:

Answer 1

= 256/400 = 0.64

= 300/482 = 0.6224

1) The test statistic z = ()/SE

                                  = (0.64 - 0.6224)/0.033 = 0.53

2) P-value = 2 * P(Z > 0.53)

                 = 2 * (1 - P(Z < 0.53))

                 = 2 * (1 - 0.7019)

                = 0.5962