Once the advertising campaign is over, companies normally evaluate it compared to the established goals. An effective tactic in measuring the usefulness of the advertising campaign is to measure the pre-and post-sales of the company's product.
In order to make this more effective, some companies divide up the country into regions and run the advertising campaigns only in some areas. The different geographic areas are then compared (advertising versus non advertising), and a detailed analysis is performed to provide an evaluation of the campaign's effectiveness. Depending on the results, a company will modify future advertising efforts in order to maximize effectiveness.