The recent wave of randomized trials in development economics has provoked criticisms regarding external validity.  We investigate two concerns - heterogeneity across beneficiaries and implementers - in a randomized trial of contract teachers in Kenyan schools.  The intervention, previously...

The recent wave of randomized trials in development economics has provoked criticisms regarding external validity. We investigate two concerns – heterogeneity across beneficiaries and implementers – in a randomized trial of contract teachers in Kenyan schools. The intervention, previously...

The recent wave of randomized trials in development economics has provoked criticisms regarding external validity. We investigate two concerns — heterogeneity across beneficiaries and implementers — in a randomized trial of contract teachers in Kenyan schools. The intervention, previously...