Sampling is a powerful tool and a critical part of communication-campaign research because it has a direct relationship to the generalizability of research results. Practitioners use sampling in partnership with the research methods they select to collect critical information that helps them solve complex problems, monitor their internal and external environments, and engage in sophisticated campaign planning and evaluation. When done properly, sampling helps practitioners get accurate information quickly at a relatively low cost. It provides them with a cost-effective way to collect information from a relatively small number of target audience members, called a sample, and draw conclusions about an entire target audience. These processes are based on principles of statistical sampling and inference.