If one want to do the economic impact assessment of any extension practice, he has to check how much of the intended practice is adopted by the target group, then out of the adopted population, how much percentage of them adopted as per the recommendation without any deviation, later, whatever the population which has adopted it as it is, how much it has shown the impact on economic returns is to be studied.
For that purpose, econometric tools used in any economic impact study can be used i.e. from simple tabular analysis to multivariate regression analysis.
Usually no economic output is the result of a single extension intervention. There will be numerous factors affecting economic output. Hence, multivariate tools are good for the purpose.
Economic tools for analyzing agricultural extension are numerous. There are statistical tools for adoption of different popularized technologies. There are qualitative tools for assessing the quality of adoption. This depends on the desired results