Introduction

In 1903, H. G. Wells hypothesized that statistical thinking would one day be as necessary for good citizenship as the ability to read and write. Statistics do play an important role in many decision-making processes. Before a new drug can be marketed, for instance, the United States Food and Drug Administration requires that it be subjected to a clinical trial, an experimental study involving human subjects. The data from this study must be compiled and analyzed to determine whether the drug is not only effective, but safe. In addition, the U.S. government’s decisions regarding Social Security and public health programs rely in part on predictions about the longevity of the nation’s population; consequently, it must be able to predict the number of years that each individual will live. Many other issues need to be addressed as well. Where should a government invest its resources if it wishes to reduce infant mortality? Does the use of a seat belt or an air bag decrease the chance of death in a motor vehicle accident? Should a mastectomy always be recommended to a patient with breast cancer? What factors increase the risk that an individual will develop coronary heart disease? To answer these questions and others, we rely on the methods of biostatistics.