Question

a certain drug is used to treat asthma. in a clinical trial of the drug, 18 of 295 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 0.01 significance level to complete parts (a) through (e) below.
1 - propztest
prop < 0.12
z = - 3.117498701
p = 0.0009119638
\hat { p } = 0.0610169492
n = 295
a. is the test two - tailed, left - tailed, or right - tailed?
two - tailed test
right tailed test
left - tailed test

Explanation:

The claim is that less than 12% of treated subjects experienced headaches. In hypothesis testing, when the alternative hypothesis is of the form \(p < p_0\) (where \(p_0 = 0.12\) in this case), the test is left - tailed. A left - tailed test focuses on the left tail of the distribution to determine if the sample proportion is significantly less than the hypothesized proportion.

Answer:

Left - tailed test