7. Give a formula for a 95% confidence interval for the odds ratio describing the effect of HT controlling for the other variables in the no interaction model.

Consider the following printout results that summarize the computer output for two models based on follow-up study data on 609 white males from Evans County, Georgia: Model I OUTPUT: 2 ln L^ ¼ 400.39 Variable Coefficient S.E. Chi sq P Intercept 6.7747 1.1402 35.30 0.0000 CAT 0.5978 0.3520 2.88 0.0894 AGE 0.0322 0.0152 4.51 0.0337 CHL 0.0088 0.0033 7.19 0.0073 ECG 0.3695 0.2936 1.58 0.2082 SMK 0.8348 0.3052 7.48 0.0062 HPT 0.4392 0.2908 2.28 0.1310 Model II OUTPUT: 2 ln L^ ¼ 357.05 Variable Coefficient S.E. Chi sq P Intercept 3.9346 1.2503 9.90 0.0016 CAT 14.0809 3.1227 20.33 0.0000 AGE 0.0323 0.0162 3.96 0.0466 CHL 0.0045 0.00413 1.16 0.2821 ECG 0.3577 0.3263 1.20 0.2729 SMK 0.8069 0.3265 6.11 0.0134 HPT 0.6069 0.3025 4.03 0.0448 CC ¼ CAT  CHL 0.0683 0.0143 22.75 0.0000 In the above models, the variables are coded as follows: CAT(1 ¼ high, 0 ¼ low), AGE(continuous), CHL(continuous), ECG(1 ¼ abnormal, 0 ¼ normal), SMK(1 ¼ ever, 0 ¼ never), HPT(1 ¼ hypertensive, 0 ¼ normal). The outcome variable is CHD status(1 ¼ CHD, 0 ¼ no CHD).