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1. Introduction - Econometrics at Illinois - University of Illinois at ...

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Roger Koenker and Zhijie Xiao 23local oces throughout the st<strong>at</strong>e were randomly assigned either to a control groupor one <strong>of</strong> six experimental tre<strong>at</strong>ment groups. In the control group the existing rules<strong>of</strong> the unemployment insurance system applied. Individuals in the tre<strong>at</strong>ment groupswere oered a cash bonus if they became reemployed in a full-time job, workingmore than 32 hours per week, within a specied qualic<strong>at</strong>ion period. Two bonuslevels and two qualic<strong>at</strong>ion periods were tested, but we will restrict <strong>at</strong>tention to thehigh bonus, long qualic<strong>at</strong>ion period tre<strong>at</strong>ment which oered a cash <strong>of</strong> bonus <strong>of</strong> sixtimes the weekly benet for claimants establishing reemployment within 12 weeks.This restricted the sample size to 6384 observ<strong>at</strong>ions. A detailed description <strong>of</strong> thecharacteristics <strong>of</strong> claimants under study is presented in Koenker and Bilias (2001)which has inform<strong>at</strong>ion on age, race, gender, number <strong>of</strong> dependents, loc<strong>at</strong>ion in thest<strong>at</strong>e, existence <strong>of</strong> recall expect<strong>at</strong>ions, and type <strong>of</strong> occup<strong>at</strong>ion.Since a large portion <strong>of</strong> spells end in either the rst week or the twenty seventhweek, it should be stressed th<strong>at</strong> the denition <strong>of</strong> the rst spell <strong>of</strong> UI in the Pennsylvaniastudy includes a waiting week and th<strong>at</strong> the maximum number <strong>of</strong> uninterruptedfull weekly benets is 26. This implies th<strong>at</strong> many subjects did not receiveanyweeklybenet and th<strong>at</strong> many other claimants received continuously their full, entitled unemploymentbenet. Again, Koenker and Bilias (2001) contains further details.6.<strong>1.</strong> The Model. Our basic model for analyzing the Pennsylvania experiment presumesth<strong>at</strong> the logarithm <strong>of</strong> the dur<strong>at</strong>ion (in weeks) <strong>of</strong> subjects' spells <strong>of</strong> UI benetshave linear conditional quantile functions <strong>of</strong> the formQ log(T ) (jx) =x > ():The choice <strong>of</strong> the log transform<strong>at</strong>ion is dict<strong>at</strong>ed primary by the desire to achievelinearity <strong>of</strong> the parametric specic<strong>at</strong>ion and by its ease <strong>of</strong> interpret<strong>at</strong>ion. Multiplic<strong>at</strong>ivecovari<strong>at</strong>e eects are widely employed throughout survival analysis, and they arecertainly more plausible in the present applic<strong>at</strong>ion than the assumption <strong>of</strong> additiveeects. It is perhaps worth reiter<strong>at</strong>ing th<strong>at</strong> the role <strong>of</strong> the transform<strong>at</strong>ion is completelytransparent in the quantile regression setting, where Q h(T ) (jx) = x > ()implies Q T (jx) =h ,1 (x > ()). In contrast, the role <strong>of</strong> transform<strong>at</strong>ions in models <strong>of</strong>the conditional mean function are r<strong>at</strong>her complic<strong>at</strong>ed since the transform<strong>at</strong>ion aectsnot only loc<strong>at</strong>ion, but scale and shape <strong>of</strong> the conditional distribution <strong>of</strong> the response.Our (provisional) model includes the following eects: Indic<strong>at</strong>or for the tre<strong>at</strong>ment group. Indic<strong>at</strong>ors for female, black and hispanic respondents. Number <strong>of</strong> dependents, with 2 indic<strong>at</strong>ing two or more dependents. Indic<strong>at</strong>ors for the 5 quarters <strong>of</strong> entry to the experiment. Indic<strong>at</strong>or for whether the claimant \expected to be recalled" to a previous job. Indic<strong>at</strong>ors for whether the respondent was \young" { less than 35, or \old" {indic<strong>at</strong>ing age gre<strong>at</strong>er than 54. Indic<strong>at</strong>or for whether claimant was employed in the durable goods industry.

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