Jack “Crash” Craddock, the chief analyst for the Federal Aviation Administration, wants to know whether airline deregulation had any impact on airline safety. As a measure of airline safety, he uses the number of near misses (a near miss is when planes come within a certain number of feet of each other) for each year. Using data from 1965 to 2000, Craddock collects the following independent variables: X₁, a countervariable coded 1 in 1960 and increasing by 1 each year; X_2, a longterm impact variable coded 0 before deregulation (1978) and increasing by 1 each year thereafter; and X₃, a control for the state of the economy—percentage growth in gross national product over the previous year (people fl y more during good economic times). A regression shows the following:

Interpret the slopes, intercept, and coefficient of determination. Test each slope for significance. What can you say about airline deregulation?

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Sb₂ = 1.2 Sb₂ = 137.1 15.9X₁ + 12.3X₂ + 26.1X3 = 14.6 Sb₂ = 3.2 Sx = 20.1 20.1 R 93 N = 33 =