Question

A school psychologist wishes to determine whether a new anti-smoking film actually reduces the daily consumption of cigarettes by teenage smokers. The mean daily cigarette consumption is calculated for each of eight teenage smokers during the month before and the month after the film presentation, with the following results: MEAN DAILY CIGARETTE CONSUMPTION

SMOKER NUMBER BEFORE FILM (X1) AFTER FILM (X2)

1 28 26

2 29 27

3 31 32

4 44 44

5 35 35

6 20 16

7 50 47

8 25 23

A) Is there a significant difference in the number of cigarettes smoked before the film as compared to the number of cigarettes smoked after the film?

B) What does this NOT necessarily mean?

C) What might be done to improve the design of this experiment?

Answer 1

Ho: There is no difference in no. of cigarettes smoked before and after watching the film
H1: There is difference in no. of cigarattes smoked that is the consumption is decreased.

Hence we can conclude that the cigarette consumption has decreased at 5% level of significance .

b)
Since we have concluded that the consumption of cigarettes has decreased on an average this does NOT mean that each and every person involved in the experiment may have reduced the consumption.

c) To improve the design we can take a large sample because a small sample is not so reliable in giving results.