To test the effectiveness of a new drug, a researcher gives one group of patients the new drug and another group a placebo. Results are shown below:
Medication
Effective
Not effective
Active Drug
151
25
Placebo
12
33
Is the proportion of patients who showed effectiveness of active drug significantly higher than the
proportion of patients who showed effectiveness in placebo group? Use alpha=0.05.
The approximate z test statistic for this test can be: