In their seminal paper, Burnside and Dollar (2000) introduced the interactive term aid*policy into growth equations. Most studies up until then had merely added aid as a variable on its own with GDP growth as the dependent variable in order to check aid effectiveness.
Reference:
Mti, S. 2011. Aid, infrastructure and growth. University of Cape Town.
Mti, S. N. (2011). Aid, infrastructure and growth. (Thesis). University of Cape Town ,Faculty of Commerce ,School of Economics. Retrieved from http://hdl.handle.net/11427/10960
Mti, Sehlule Nontutuzelo. "Aid, infrastructure and growth." Thesis., University of Cape Town ,Faculty of Commerce ,School of Economics, 2011. http://hdl.handle.net/11427/10960
Mti SN. Aid, infrastructure and growth. [Thesis]. University of Cape Town ,Faculty of Commerce ,School of Economics, 2011 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/10960