Q. No.2. A study of the effect of smoking on sleep patterns is conducted. The measure observed is the time, in minutes, that it takes to fall asleep. These data are obtained: [3] Smokers:69.3 56.0 22.1 47.6 53.2 48.1 52.7 34.4 60.2 43.8 23.2 13.8 Non Smokers: 28.6 25.1 26.4 34.9 28.8 28.4 38.5 30.2 30.6 31.8 41.6 21.1 36.0 37.9 13.9

(a)    

(b)    

(c) Smoking increases the time to fall asleep

Explanation:

Solving (a): The sample mean of each group

Mean is calculated as:

So, we have:

Smokers

and

Non Smokers

and

Solving (b): The standard deviation of each group

This is calculated as:

For smokers

So:

For non-smokers

So:

Solving (c): Impact of smoking on time to sleep

In (b), we have:

--- smokers

--- non-smokers

Smokers have larger standard deviation (i.e. large variability) than non-smokers. This means that smokers require more time to fall asleep.