None of the earlier answers stress this, but the key issue in assessing the impact of a project is to answer the question "compared to what?"  If the project is undertaken you want to compare the outcome to what would have happened if the project was not undertaken.  That, in turn requires that you formulate a "counterfactual' comparison, that describes the world in the absence of the project.  If, for example, you are considering a government infrastructure project the counterfactual must answer the question what would happen to government expenses and revenues in its absence: would the funds be spent by the government on another project? would taxes be lower, so that the money would be spent by private citizens?  Once you answer these questions you need to develop an appropriate economic model of the quantities you believe the project will affect and compare the actual outcomes to those predicted by the counterfactual.  

The specific model you use would depend on the circumstances, but could be an input output model, a Computational General Equilibrium model, or a partial equilibrium model.  There is no general right answer.  But there is a large literature on impact assessment for state and local governments in the US.

For Economic impact evaluation

you can used tool such as the “Cobb-Douglas production function model”, The Cobb-Douglas functional form of production functions was used to represent the relationship of an output to inputs. The Cobb-Douglas equation can be used to analyse the impact of some production variables on productivity growth.

For Social Impact  evaluation

This will identify and assess a project’s social impacts that are directly related to the project and propose measures to enhance potential positive impacts and strategies to avoid, manage, mitigate or offset the predicted negative project impacts. Components to be considered as part of an Social impact evaluation include:

 community and stakeholder engagement

 workforce management

 housing and accommodation

 local business and industry content

 health and community well-being.

For environmental impact evaluation

This formal process used to predict the environmental consequences (positive or negative) of a plan, policy, program, or project prior to the decision to move forward with the proposed action. The purpose of the assessment is to ensure that decision makers consider the environmental impacts when deciding whether or not to proceed with a project. The International Association for Impact Assessment (IAIA) defines an environmental impact assessment as "the process of identifying, predicting, evaluating and mitigating the biophysical, social, and other relevant effects of development proposals prior to major decisions being taken and commitments made.

The "Theory and Applications of the Analytic Network Process: Decision Making with Benefits, Opportunities, Costs, and Risks by Thomas L. Saaty," RWS Publications, Pittsburgh, PA 2005 contains numerous applications besides the methods you identified. There is also a free software provided that will implement the programs.

There are cost minimization, input ratio method.

Comparing the performance on baseline data (if there is) is a simple method.

you can apply chi square test. But you should have proper data.

As statistical tools, I suggest to use dif-in-dif or/and propensity match score

None of the earlier answers stress this, but the key issue in assessing the impact of a project is to answer the question "compared to what?"  If the project is undertaken you want to compare the outcome to what would have happened if the project was not undertaken.  That, in turn requires that you formulate a "counterfactual' comparison, that describes the world in the absence of the project.  If, for example, you are considering a government infrastructure project the counterfactual must answer the question what would happen to government expenses and revenues in its absence: would the funds be spent by the government on another project? would taxes be lower, so that the money would be spent by private citizens?  Once you answer these questions you need to develop an appropriate economic model of the quantities you believe the project will affect and compare the actual outcomes to those predicted by the counterfactual.  

The specific model you use would depend on the circumstances, but could be an input output model, a Computational General Equilibrium model, or a partial equilibrium model.  There is no general right answer.  But there is a large literature on impact assessment for state and local governments in the US.

I suggest to refer the following articals which may be useful for your question.

1. Social Impact Assessment Methodology: http://www.sasanet.org/documents/Tools/Social%20Impact%20Assessment%20Methodology.pdf

2. DAMS AND DEVELOPMENT PROJECT COMPENDIUM ON RELEVANT PRACTICES

Social Impact Assessment of Affected People

In addition, read my article on Application of Cobb-Douglas Function for Analyzing the Process of Agricultural Production: A Case Study from Sri Lanka.

Good luck

The appropriate method depends upon the scheme/program being evaluated. The best method in theory is often impracticable. In the U.S., courts and regulatory agencies have specific criteria for compliance that require specific assessment methods. Budgetary authorities and legislatures often use static accounting (spreadsheet) methodologies glossing over social particularly environmental costs/benefits. Best practices often employ macro economic models or regional economic impact assessment models. I have also used game theoretic approaches to simulate economic/financial warfare.

Please see:

COMMON METHODS USED IN IMPACT ASSESSMENT

http://www.sed.manchester.ac.uk/research/iarc/ediais/word-files/CommonMethodsinIA.doc

A new field of impact assessment consists in using tthe extended net present value of the project through the consideration of  the real options created or destroyed by the project .The methodology of real options is a recent innovation in the technical evaluation of projects and programs. It departs from traditional techniques to estimate project impact, because it focuses on measuring the acquisition of capacities (defined as "capabilities" or potential) under conditions of dynamic uncertainty. It is therefore based on indicators, which do not require the measurement of something that has already happened, such as the increase in revenues, exports or other elements of "flow" of project performance, but instead quantify the potential that project stakeholders have developed as a result of building human capital and not human, as well as other intangible elements of their profile. These are evaluated as potential sources of value of opportunities, ie the ability to create value in the face of opportunities created by the unfolding of reality under uncertainty.

The concept of real option derives from that of financial option. In analogy with the latter, a real option is defined by an economic agent as the exclusive right, but not the obligation, to undertake an irreversible action with uncertain benefits at a preset cost. Since the exercise of an option is equivalent to the exercise of a capacity, as an exclusive right, and is irreversible under uncertainty, ta project can be considered a set of these rights, which constitute the competitive advantages and define, compared to the other enterprises, the field of action and the chances of success. Human capital and human capital as well as other forms of tangible and intangible assets constituting productive enterprises represent, in this context, a set of options, and their value depends on the possibilities they offer to the project stakeholders to exploit the opportunities that may materialize in the future. This particular form of value, which is called the option value, then quantifies the business assets, taking into account its likely future success. Even this success does not occur, the value created by the project, in other words, lies in the increased capabilities of its stakeholders.

Much depends on the objective of impact assessment. The measures given are appraisal methods. If the focus is on social outcomes then social lmpact assessment is appropriate; environmental outcomes require environmental impact assessment; economic outcomes requires economic impacts assessment (income, distribution and employment). However, in case of development projects, impact assessment takes the route of "before-after" analysis through carefully designed experimental research methods. Here, counterfactual analysis is normally done and then ex ante/ ex post analysis of impact has to be compared with it.

Te problem with project assessment is that it must take into account many different factors linked not only with economics and finance but with social, environmental and quality issues. It most also consider the direct, indirect and induced effects of the project.

I have developed a tool called ' Z matrix' that can be useful in determining, starting from the actions generated by a projects, its effects, receptors of those effects, consequences and response.

If you think that it can help you, I can send trhe method to you

Project impact assessment can be determined using either qualitative tools, quantitative tools or both. However, it also depends on what you want to measure in the impact. This can be quality of life or standard of living. Different criteria can be use for quality of life and standard of living. You may want to see on line THE ROLE OF COOPERATIVE SOCIETIES ON RURAL FINANCE: EVIDENCE FROM OGUN STATE, NIGERIA.

project impact assessment can be identified by check list and matrices, metrics, the experts system, professional experience, ad hoc and GIS analysis. The method and level of impact assessment will depend on the type of project your are working on.

There is the Pre & Post-Project method, and the there is the Social Impact measurement as well.

Dear Balaji

There are many different methods and their application depends naturally of the particular case.

I am enumerating the different methods as per my knowledge but there may be others. I am attaching and example of each one.

1. Geographic Information Systems -Road construction near archaeological sites

2. Contingent Valuation – Visitors to an environmentally sensitive site

3. Cost-Benefit Analysis – Hedonic price – Sewerage conversion in a touristic site

4. Cost-Effectiveness Analysis -Selection of an exhaust filtering system for a factory

5. Input-Outfit analysis - Contamination produced by the car industry

6. Life Cycle Analysis -Construction of a copper concentration plant

7. Multicriteria Analysis -Selection of different urban projects

ü Improving airport efficiency (The Netherlands)

ü Conversion and modernization of a city port (Taiwan)

ü Determining access routes for airports,

Etc.

8. Mathematical Programming

ü Selection of domestic waste incinerators (several countries)

ü Selection of a sewerage system (Norway)

ü Options to alleviate traffic congestion (The Netherlands)

ü Construction of an overhead power line (South Africa)

ü Routing of an oil pipeline (Middle East)

ü Construction of an LPG pipeline (India)

ü Ranking hydro electric projects (Nepal)

ü Policy for energy generation (Canada)

ü Policies for domestic garbage disposal (Canada)

9 Risk analysis

10 The Z method – Used in a coastal nuclear plant

Etc....

In addition a very important aspect to consider for a project impact assessment is the generation of externalities such as those produced by logging that may originate erosion and mudslides. There is also the depletion of natural resources such as minerals, or the production of noise as in highways. Included are the salinization of rivers, due to agriculture or by putting a physical barrier for trout spawning in case of dams construction

Thank you for the elaborate answer Nolberto Munier.