Question

Quit Smoking: The New England Journal of Medicine published the results of a double-blind, placebo-controlled experiment to study the effect of nicotine patches and the anti-depressant bupropion on quitting smoking. The target for quitting smoking was the 8th day of the experiment. In this experiment researchers randomly assigned smokers to treatments.

Of the 244 smokers taking the anti-depressant bupropion, 74 stopped smoking by the 8th day. Of the 244 smokers using the nicotine patches, 40 stopped smoking by the 8th day. A hypothesis test supports the conclusion that "quit smoking" rates are significantly higher for smokers taking bupropion compared to smokers using nicotine patches. (P-value =0.0001)

In statistics what does the phrase "significantly higher" mean?

		(i) In this experiment the difference observed in the success rates from the two treatment groups is large. One treatment had a much higher success rate than the other.
		(ii) In this experiment the difference observed in the success rates from the two treatment groups is larger than we expect in random sampling if the treatments had the same success rates.
		(iii) In this experiment the difference observed in the success rates from the two treatment groups is larger than we expect in random sampling if neither treatment is effective.

Answer 1

Option number two is feasbile.

It is clear that noth the treatment had aome effect.

Our null hypothesis always is that the treatments have same effect.

Alternative hypothesis is bupropion is better treatment than nicotine patch.

The experiment is a double blinded placebo experiment, thus there is no chance of cohort biases. Thus, here significantly higher means that difference observed in the mean effect of the treatments is much greater than what would hsve been expected if the treatments had same mean.