Recall the report On the Front Line: The Work of First Responders in a Post-9/11 World. We will use data from this report to investigate the question: Are alcohol-related problems among New York firefighters associated with participation in the 9/11 rescue?
Here again are our observed data:
No risk.
for alcohol problems
Moderate to Severe risk
for alcohol problems
793
309
1102
Participated
in 911 rescue
441
110
551
Did Not Participate
in 911 rescue
419
1653
1234
State the appropriate hypotheses for the chi-square test for independence in this case. Now you will check whether the conditions for the chi-square test are met. In order to do this, you’ll need to first launch the actual research report and read the last paragraph on page iii of the introduction (starting with the "The study was fully funded…")
The study was fully funded by the Smithers Institute at the School of Industrial and Labor Relations. The findings presented in this report are based on survey data collected from New York City firefighters and officers during the summer and fall of 2003. In total, out of a target sample of some 3,600 firefighters and officers, data were collected from 1,653 firefighters and 379 officers; approximately 2/3 of whom were on the scene at the World Trade Center on 9/11. The target sample represents one third of all NYC firefighters. Rather than identifying a random sample of firefighters, we drew a stratified, random sample of 144 fire companies (out of approximately 350 FDNY companies) and targeted all of the members of these companies (typically between 20-30 firefighters and officers per company) for data collection. Stratification was based on the relative work intensity of each company (i.e., average daily runs). We used the FDNY’s three-category system to differentiate between more and less active firehouses, randomly sampling an equal number of the firehouses from each of these three categories (i.e., 48 from highly active, 48 iv from moderately active and 48 from relatively inactive) for inclusion in the study. As might be expected in this highly male-dominated workforce, 99 percent of those included in our sample were men.