The Results of a Recent Study Regarding Smoking and Three

Essay

The results of a recent study regarding smoking and three types of illness are shown in the following table.
$\begin{array}{lrr}\text { Illness } & \text { Non-Smokers } & \text { Smokers } &\text { Totals }\\\text { Emphysema } & 30 & 90&120 \\\text { Heart problem } & 70 & 210&280 \\\text { Cancer } & 100 & 300&400\\\text { Totals }&200&600&800\end{array}$ We are interested in determining whether or not illness is independent of smoking.
a. State the null and alternative hypotheses to be tested.
b. Show the contingency table of the expected frequencies and determine the test statistic.
c. The null hypothesis is to be tested at 95% confidence. Determine the critical value for this test.
d. What do you conclude?