This week, Katie welcomes ChangeMaker, David Kirk, a Professor of Sociology and Professorial Fellow of Nuffield College at the University of Oxford. David uses experiments and social network analysis to examine why people commit crime as well as innovative solutions to helping them to stop. In part one, David discusses his findings in the Maryland Opportunities through Vouchers Experiment and his book, Home Free, which traces the effect of residential displacement among formerly incarcerated individuals in the wake of Hurricane Katrina.