Question

a certain drug is used to treat asthma. in a clinical trial of the drug, 21 of 270 treated subjects experienced headaches (based on data from the manufacturer). the accompanying calculator display shows results from a test of the claim that less than 12% of treated subjects experienced headaches. use the normal distribution as an approximation to the binomial distribution and assume a 0.05 significance level to complete parts (a) through (e) below. a. is the test two - tailed, left - tailed, or right - tailed? two - tailed test right tailed test left - tailed test

Explanation:

A left - tailed test is used when the alternative hypothesis is of the form \(H_1: p < p_0\). Here, the claim is that less than \(12\%\) (\(p = 0.12\)) of treated subjects experienced headaches, so the alternative hypothesis is \(H_1: p<0.12\). In a one - proportion z - test, the direction of the inequality in the alternative hypothesis determines the type of the test. If \(H_1: p < p_0\), the test is left - tailed; if \(H_1: p>p_0\), the test is right - tailed; and if \(H_1: p
eq p_0\), the test is two - tailed.

Answer:

Left - tailed test