It was observed that mortality rates for the Tolbumide and the placebo groups fo

Question

It was observed that mortality rates for the Tolbumide and the placebo groups followed a   normal distribution with mean 18.9% and standard deviation 7.6 and mean 9.8% and standard deviation 3.8, respectively.                                                             (8 points)

What is the 95% Confidence interval for the mortality rate for each of the two groups? (Remember the 95% CI formula (mean ± 2 se))

Do these data support researchers’ conclusion (c)? Why or why not?

When the two mortality rates were compared using a t-test, the p-value was found to be P<.01. What would this tell you about the significance level of the study? Which type of error is controlled by the p-value?

Does this test achieve at least 80% power (at =.05)? If yes, why? If no, why not? And what sample size per group would give the researchers at least 80% power? (Hint: use the two mortality rates given at the beginning of #6 and your tables.)

Explanation / Answer

95% CI for Tolbumide group = 18.9 - 7.6*2, 18.9 + 7.6*2 = 3.7, 34.1

95% CI for Tolbumide group = 9.8 - 3.8*2, 9.8 + 3.8*2 = 2.2, 17.4

p value of less than 0.01 means that the null hypothesis that the means are equal is rejected if the significance level is 0.01 or more. It controls type I error.

The power of test to be calculated at what difference of means is not given . Hence data is insufficient to calculate power of then test.

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