Discrete Random Variables

Descriptive statistics deals with variables that can take values within a discrete or a continuous set. This chapter introduces random variables formally, as associations of random events with numerical values. Then, it shows how the distribution of a discrete random variable can be characterized by a probability mass function or a cumulative distribution function, which are related to concepts from descriptive statistics, i.e., histograms of relative frequencies and cumulative relative frequencies. The chapter proceeds along the same conceptual path, introducing expected values of discrete random variables first, and then variance and standard deviations. Finally, the chapter describes the main discrete probability distributions that are common in applications, along with some motivating examples relevant to business management. Controlled Vocabulary Terms cumulative distribution function; descriptive statistics; discrete distributions; discrete random variable; probability mass function; standard deviation; variance