For many people who smoke, the most natural thing to do in the midst of a stressful situation is to reach for a cigarette. Many smokers will explain that smoking helps them to relax and relieves their feeling of stress. Their adamant belief that this truly works has introduced the question of whether smoking does indeed relieved the amount of stress perceived by a smoker. The goal of this study was to investigate the relationship between smoking and the amount of recent life stress perceived, using some other variables such as age, and gender as independent (or explanatory) variables or covariates. Stress is a dependent response variable at three levels. Smoking can be viewed as either independent or independent categorical variable at three levels, and age (3 levels) and gender (2 levels) are independent variables (factors) as follows:
Penn State researchers explored the relationship (if any) between four variables in the dataset, stress.txt:
- smoking status (1 = smoker, 2 = quitter, 3 = non-smoker) in column 1,
- gender (1 = male, 2 = female) in column 2,
- age (1 = young, 2 = middle, 3 = old) in column 3, and
- perceived stress level (1 = severe / a lot, 2 = moderate / some, 3 = mild / none) in column 4.
Stress is a "polytomous response" — having three values.
The data can be cross classified as a four-way table.
The relevant SAS programs and data for this case can be found below: