Background Nicotine replacement therapy is an effective trea

Background Nicotine replacement therapy is an effective treatment for nicotine-dependent smokers. However, cessation rates are modest, and preliminary studies suggest that combination therapy may be superior. We compared the efficacy of the nicotine inhaler plus nicotine patch vs nicotine inhaler plus placebo patch for smoking cessation.

Methods A double-blind, randomized, placebo-controlled trial was conducted in 400 subjects who had smoked 10 or more cigarettes per day for 3 years or longer. Group 1 (n = 200) received the nicotine inhaler plus nicotine patch (delivering 15 mg of nicotine per 16 hours) for 6 weeks, then inhaler plus placebo patch for 6 weeks, then inhaler alone for 14 weeks. Group 2 (n = 200) received the nicotine inhaler plus placebo patch for 12 weeks, then inhaler for 14 weeks. Inhaler was used at a rate of 6 to 12 cartridges per day ad libitum for 3 months and then tapered off. The main outcome measure was complete abstinence (self-reported).

Results Group 1 vs group 2 complete abstinence rates were 60.5% and 47.5% at 6 weeks (P = .009), 42.0% and 31.0% at 12 weeks (P = .02), 25.0% and 22.5% at 6 months (P = .56), and 19.5% and 14.0% at 12 months (P = .14).

a) What is the null hypothesis, in words?

b) What is the null hypothesis, in symbols?

c) How would you sum up the results of this study in plain English? Be sure to treat the implications of the P-value being different at different time points.

d) What would a type II error be for this study?

e) Estimate the standard error of the Group 2 complete abstinence rates after 12 weeks, using the formula on p 189 of your text.

Solution

answer of part (a)

null hypothesis : there is no difference between nicotine inhaler plus nicotine patch and nicotine inhaler plus placebo patch for smoking cessation

answer of part (b): Ho:nicotine inhaler plus nicotine patch=nicotine inhaler plus placebo patch for smoking cessation

answer of part (c)

At 6 weeks the p-value is 0.009 which is significant at 5% level of significance , it means there is significant difference in combination therapy nicotine inhaler plus nicotine patch and inhaler plus placebo.

At 12 week the p-value is 0.02  which is significant at 5% level of significance , it means there is significant difference in combination therapy nicotine inhaler plus nicotine patch and inhaler plus placebo.

After 12 weeks the p-values are 0.56 and 0.14 which are insignificant at  5% level of significance it means there is insignificant difference in combination therapy nicotine inhaler plus nicotine patch and inhaler plus placebo.

Finaly we can say that up to 12 weeks there is significant differenence in  combination therapy nicotine inhaler plus nicotine patch and inhaler plus placebo after that both treatment shows insignifianct affect.

part(d) and part(e) need more information to solve.