One year ago a local government initiated an antismoking advertising campaign in local newspapers, which it financed by imposing a tax on cigarettes of 20 cents per pack. One year later, the number of people in the locality who smoke cigarettes had declined by 3 percent. Clearly, what was said in the advertisements had an effect, although a small one, on the number of people in the locality who smoke cigarettes.
The statement 'Merchants in the locality responded to the local tax by reducing the price at which they sold cigarettes by 20 cents per pack' most helps to strengthen the argument.