1. The appropriate measure of association for a case-control study is the odds ratio.
2. The odds ratio is calculated as the cross-product ratio: ad / bc. Odds ratio = 15 x 23 / 8 x 7 = 6.16 = 6.2
3. With a chi-square of 9.41 and a 95% confidence interval of 1.6–25.1, this study shows a very strong (odds ratio = 6.2) association between histoplasmosis and working in Building X. This finding is quite statistically significant (chi-square = 9.41 corresponds to a p-value between 0.01 and 0.001). And although the 95% confidence interval indicates that the study is compatible with a seemingly relatively wide range of values (1.6–25.1), most of these values indicate a strong if not stronger association than the one observed