Nicotine patches are often used to help smokers quit. Does adding antidepressants to the nicotine patches help? A randomized double-blind experiment assigned 256 to receive a patch that includes the antidepression drug bupropion and 250 smokers who wanted to stop to receive regular nicotine patches. After a year, 89 in the patch & drug group had abstained from smoking and 47 subjects in the nicotine patch group.

 p^_{patch & drug}=   (3 decimals - this is the treatment group)

p^_patch=   (3 decimals - this is the control group)

Use StatCrunch ( Stat > Proportion Stats > Two Sample > With Summary) to find a 95% confidence interval for the difference (treatment minus control) in the proportion of smokers who quit.

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