A new blood pressure lowering medication is tested on a group of patients. The a

Question

A new blood pressure lowering medication is tested on a group of patients. The average systolic blood pressure of patients who did not receive the medication is 138 mm hg, and the average systolic blood pressure of patients who did receive the medication is 126 mm hg. A t-test was used to compate the two outcomes. The 95% confidence interval was 10.23 to 13.77 and the 99% confidence interval was 9.68 to 14.33. The null hypothesis is that there is no difference between the groups. What is the correct interpretation of this study's results? 1) Using the 99% confidence interval one fails to accept the null hypothesis. 2) Increasing the confidence interval from 95% to 99% decreases the probability of accepting the null hypothesis. 3) Increasing the confidence interval from 95% to 99% decreases the probability of rejecting the null hypothesis. 4) using the 95% confidence interval one fails to reject the null hypothesis. Please explain how you get the anser in detail. I am having a difficult time understanding how to tell in the null hypothesis is rejected or accepted. Please help

Explanation / Answer

95% or 99% Confidence interval for difference between means /averages: For 95% or 99% percent of samples the diference between means/averages is within the confidence interval.

Given 95% confidence interval of difference between means/averages = 10.23 to 13.77

For the given sample ,

Mean/Average systolic blood pressure of patients who did not receive the medication = 138 mm hg

Mean/Average systolic blood pressure of patients who did receive the medication is = 126 mm hg

Difference between sample means/averges = 138-126 = 12

so, for the given sample difference bewteen the means :12 is within 10.23 to 13.77 which is the 95% confidence interval.

Hence one fails to reject the null hypothesis.

4) using the 95% confidence interval one fails to reject the null hypothesis is the correct answer.

if your significance level is 0.05, the corresponding confidence level is 95%. If the P value is less than your significance (alpha) level, the Null hypothesis is rejected. If the confidence interval does not contain the null hypothesis value, the Null hypothesis is rejected.

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