ABSTRACT
Most of the graphs and statistics covered so far have dealt with one variable at a time. For example, we saw a histogram of the obesity rates of the 50 U.S. states and the District of Columbia. The obesity rate was defined as a state’s percentage of adults surveyed by the Behavioral Risk Factor Surveillance System (BRFSS), who had a body mass index (BMI) of 30 or higher, based on the participants’ self-reported height and weight. Obesity rates became more interesting when graphed along with a second variable, food hardship. The Food Research and Access Center defined food hardship as the percentage of adults who said they lacked money to buy food for their families at some point in the previous year. Figure 3.8 showed a scatterplot of food hardship and obesity rates for the 50 U.S. states plus the District of Columbia; it is reproduced here as Figure 5.1.
