Identification in a nutshell Start by comparing expenditures for households marginally close to S=0; since Y=Yo+rB we have that E{|S=0}=E{S=0}+E{RB|S=0 E{y|S=0}=E{lS=0}+ES=0 Consider the difference around eligibility E{yS=0}-E{y|s=0}=E{S=0-}-E{xS=0} +ERBIS'=0*)Identification in a nutshell Start by comparing expenditures for households marginally close to S *=0; since Y = Y0+Rβ we have that Consider the difference around eligibility:             * * * 0 * * * 0 | 0 | 0 | 0 | 0 | 0 | 0 E Y S E Y S E R S E Y S E Y S E R S   + + + − − − = = = + = = = = + =           * * * * 0 0 * | 0 | 0 | 0 | 0 | 0 E Y S E Y S E Y S E Y S E R S  + − + − + = − = = = − = + =