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Heckman's Methodology For Correcting Selectivity Bias : An Application To Road Crash Costs, Margaret Giles
Heckman's Methodology For Correcting Selectivity Bias : An Application To Road Crash Costs, Margaret Giles
Research outputs pre 2011
Aggregate road crash costs are traditionally determined using average costs applied to incidence figures found in Police-notified crash data. Such data only comprise a non-random sample of the true population of road crashes, the bias being due to the existence of crashes that are not notified to the Police. The traditional approach is to label the Police-notified sample as 'non-random' thereby casting a cloud over data analyses using this sample. Heckman however viewed similar problems as 'omitted variables' problems in that the exclusion of some observations in a systematic manner (so-called selectivity bias) has inadvertently introduced the need for an …