A capacity building program on drip irrigation (TNDRIP) was undertaken in certain regions of the Indian State of Tamil Nadu during 2009-2010. An assessment of the impact of the program in terms of effective use of drip irrigation and increased crop yields was made in 2011 by applying double difference method (a combination of both with and without and before and after approaches). The results had indicated that the drip capacity building program resulted in a yield increase of 2.5 t/ha for Banana 1, 1.9 t/ha for Banana 2, 3.3 t/ha for sugarcane and 0.3 t/ha for turmeric. The conventional method using the before and after situations had shown a yield increase of 4.3 t/ha for Banana 1, 12.1 t/ha for Banana 2, 40.6 t/ha for sugarcane and 2.6 t/ha for turmeric. The conventional approach is highly upward biased in estimating the impact of the drip capacity building program and thus the double difference method will be an appropriate method to evaluate the impact of the programs that involve both with and without as well as before and after situations.
 Seckler, D., Molden, U.A.D., de Silva, R. and Barker, R. (1998) World water demand and supply, 1990 to 2025: Scenarios and Issues. Research Report 19, International Water Management Institute (IWMI), Colombo, Sri Lanka.
 Cuykendall, C.H., White, G.B., Shaffer, B.E., Lakso, A.N. and Dunst, R.M. (1999) Economics of drip irrigation for juice grape vineyards in New York State. Department of Agricultural, Resource and Managerial Economic. College of Agriculture and Life Sciences, Cornell University, Ithaca, New York, 14853-17801.
 Qureshi, M.E, Wegener, M.K. Harrison, S.R. and Bristow, K.L. (2001). Economic evaluation of alternate irrigation systems for sugarcane in the burdekin delta in North Queensland, Australia. In: Brebbia,C.A., Anagnostopoulos, K, Katsifarakis, K. and Cheng, A.H.D. Eds., Water Resource Management, WIT Press, Boston, 47-57.
 Namara, R.E., Upadhyay, B. and Nagar, R.K. (2005) Adoption and impacts of microirrigation technologies: Empirical results from selected localities of Maharashtra and Gujarat States of India. Research Report 93, International Water Management Institute, Colombo, Sri Lanka.
 Sivanappan, R.K. (2002) Strengths and weaknesses of growth of drip irrigation in India. Proceedings of the GOI Short Term Training on Micro Irrigation for Sustainable Agriculture, 19-21 June 2002, Water Technology Centre, Tamil Nadu Agricultural University, Coimbatore.
 Shah, T., Verma, S., Bhamoriya, V., Ghosh, S. and Sakthivadivel, R. (2005) Social impact of technical innovations: Study of organic cotton and low cost drip irrigation in the agrarian economy of west Nimar. Region. International Development Enterprises (India), Delhi.
 Suresh Kumar, D. and Palanisami, K. (2011) Can drip irrigation technology be socially beneficial? Evidence from Southern India. Water Policy, 13, 571-587.
 Suresh Kumar, D. (2008) Promoting drip irrigation: Where and why? Managing water in the face of growing scarcity, inequity and declining returns: Exploring fresh approaches. The IWMI-Tata Water Policy Program, Seventh Annual Partners Meet, ICRISAT Campus, Hyderabad, 108-120.
 John, M.A. and Flores, R. (2005) Impact evaluation of a conditional cash transfer program: The Nicaraguan Red de Social. Research Report 141, International Food Policy Research Institute, Washington DC.
 Pattanayak, K.S. (2009) Rough guide to impact evaluation of environmental and development program programs. Sandee Working Paper No.40-09, South Asian Network for Development and Environmental Economics, Nepal.