The Cost of Smoking

Scientists make computer models to help simulate complicated or difficult experiments. It would take a lifetime to follow the impact of cigarettes on real people. You need to do your experiment today so you can make informed decisions.

Scientists observe a situation like smoking. They collect data and make mathematical formulas with those numbers. The formulas can be complicated and time consuming to solve. The scientists make a computer algorithm using these formulas. This computer algorithm is called a model. The scientists run the model several times. Each time they change one variable to explore the "science".

You will be using a STELLA model. This model will simulate the costs of smoking for one person. You will be looking at two kinds of costs. First, how many dollars the cigarettes cost. Second, the number of years that smoking subtracts from the person's life.

How does the model calculate the cost of the cigarettes? You tell the model the number of cigarettes smoked each day. You also tell the model the cost of a pack of cigarettes. By multiplying the number of cigarettes smoked each day by 365 the model finds the number of cigarettes smoked in a year. Next the number of cigarettes is divided by 20. Now the model knows the number of packs of cigarettes smoked in a year. Next the model multiplies the number of packs by the cost of one pack. This gives the cost of cigarettes in one year. Adding all of the yearly costs gives the lifetime cost of cigarettes.

The cost in terms of years of life is based on analysis done by the American Heart Association. They estimate that smoking a cigarette reduces the person's life expectancy by 7 minutes. You have already told the model how many cigarettes are smoked in one day. The model multiplies that number by 7 to determine the minutes lost each day. Multiplying the minutes lost by 365 give the minutes the person's life is shortened each year.

There are 1440 minutes in a day. 1440 times 365 = 525600 minutes in a year. The model divides the minutes lost in a year by 525600. This tells the model the fraction of a year lost for one year of smoking. Adding these yearly losses together gives the number of years the person's life is shortened.

The prognosis isn't all bad if a person stops smoking before cancer or heart disease starts. The body can correct some of the damage smoking has caused. If the person stops smoking the model adds back .2 year to the person's life expectancy each year.

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