Chapter 2.2, Problem 2.30ACI

Volkswagen emissions scandal. Recently, the Environmental Protection Agency (EPA) cited Volkswagen (VW) for installing “defeat devices” that allowed VW vehicles to pass emissions inspections for 7 years while emitting 40 times the official limit of nitrogen oxide (NOx). Immediately, speculation began on how many people may have died over this time period due to ambient pollution caused by the excess nitrogen oxide in the air. A study published in Significance (December 2015) estimated the number of U.S. deaths attributable to NOx pollution produced from VW vehicles over the 7-year period. The researchers computed the estimate for each of 27 different scenarios involving different values of three variables: total distance (in miles) driven by these illegal VW vehicles, the amount by which the VW vehicles exceeded the EPA standard for NOx, and the estimated association between NOx emissions and mortality. The data (simulated from results reported in the study) are listed in the accompanying table.

1. a. Use a relative frequency histogram to describe the distribution of estimated deaths for the 27 scenarios.
2. b. Identify the class interval that includes the largest proportion of estimates. Explain why this interval is most likely to include the actual number of deaths attributable to NOx pollution over the 7-years