Chapter 4. Probabilistic Learning – Classification Using Naive Bayes

When a meteorologist provides a weather forecast, precipitation is typically predicted using terms such as "70 percent chance of rain." These forecasts are known as probability of precipitation reports. Have you ever considered how they are calculated? It is a puzzling question, because in reality, it will either rain or it will not.

These estimates are based on probabilistic methods, or methods concerned with describing uncertainty. They use data on past events to extrapolate future events. In the case of weather, the chance of rain describes the proportion of prior days with similar measurable atmospheric conditions in which precipitation occurred. A 70 percent chance of rain therefore implies that in 7 out of 10 past cases with similar weather patterns, precipitation occurred somewhere in the area.

This chapter covers a machine learning algorithm called naive Bayes, which also uses principles of probability for classification...