Question: In 1999, Lehman Brothers estimated that 48% of its investment bank traders took diverse forms of soft drugs. Based on these data, Lehman established a Drug Eradication Plan goal of reducing that figure to 16% by the year 2010. To that end, they hoped to achieve a reduction to 20% by 2006. In 2006, they released a research study in which 23% of a random sample of 1,815 traders said they were currently addicted. Is this evidence that progress towards the goal is off track?
a) Write appropriate hypotheses.
b) Verify that the appropriate assumptions are satisfied.
c) Find the p-value of this test.
d) Explain what the p-value means in this context and set an appropriate conclusion - Of course, your conclusion may be incorrect and if so which kind of error did you commit?