Of late, there has been a lot of request for us to conduact an impact study of "something" - a program, a project, a treatment, a medical intervention and even a financial decision. The Wikipedia provides some very interesting definition and practical implication of such study. An exceprt underpinning an impact study is provided in this entry.
"Impact evaluation assesses the changes that can be attributed to a particular intervention, such as a project, program or policy, both the intended ones, as well as ideally the unintended ones. In contrast to outcome monitoring, which examines whether targets have been achieved, impact evaluation is structured to answer the question: how would outcomes such as participants’ well-being have changed if the intervention had not been undertaken? This involves counterfactual analysis, that is, “a comparison between what actually happened and what would have happened in the absence of the intervention.” Impact evaluations seek to answer cause-and-effect questions. In other words, they look for the changes in outcome that are directly attributable to a program. Impact Evaluation helps us to answer key questions for evidence-based policy making: what works, what doesn’t, where, why and for how much? It has received increasing attention in policy making in recent years in both Western and developing country contexts. It is an important component of the armory of evaluation tools and approaches and integral to global efforts to improve the effectiveness of aid delivery and public spending more generally in improving living standards. Originally more oriented towards evaluation of social sector programs in developing countries, notably conditional cash transfers, impact evaluation is now being increasingly applied in other areas such as the agriculture, energy and transport."
