Question

5.CE.7(c)
A study conducted in 2002 by Shiffman, Dressler, Hajeh, and Gilburt investigated whether a nicotine lozenge is helpful for smokers trying to quit smoking. The researchers recruited smokers who were interested in quitting through advertisements near four sites in the United Kingdom and 11 sites in the United States. Those smokers who met the screening qualifications were randomly assigned to one of two groups: One group received nicotine lozenges and the other group received placebo lozenges. The subjects were compared on various background variables at the beginning of the study, and at the end of the study they were compared on whether or not they successfully abstained from smoking.
​​At the end of the 52-week study, 19.7% of those in the nicotine group had successfully abstained from smoking, compared to 9.2% of those in the placebo group.
Calculate the difference in the conditional proportions who had successfully abstained from smoking. Round your answer to 3 decimal places, e.g. 0.485.
​Enter your answer in accordance to the question statement  

Answer 1

We are given here that 19.7% of those in the nicotine group had successfully abstained from smoking, compared to 9.2% of those in the placebo group. Therefore the difference in the conditional proportions who had successfully abstained from smoking is computed here as:

= Proportion of those in nicotine group who had successfully abstained from smoking - Proportion of those in placebo group who had successfully abstained from smoking

= 0.197 - 0.092

= 0.105

Therefore 0.105 is the required difference in the conditional proportions here.