Cost-benefit analysis: Difference between revisions
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==Methodology== | ==Methodology== | ||
===The basic method=== | ===The basic method=== | ||
The decision criterion of a cost-benefit analysis uses the summation of the effects of the expected outcomes of a project on people within its scope. To make a summation possible, a monetary cost or benefit is assigned to each of those effects. (The term "cost-effectiveness" is a applied to an analysis in which only the costs are monetised.) The summation normally used is then the of the costs and benefits of each effect, weighted by their estimated probability of occurrence, and discounted using the estimated time preference rates of those affected. The acceptance criterion for a single project is a positive value of the resulting net present expected value of the excess of benefits over costs, and the acceptance criterion for the acceptance of one among several alternatives is that it should be the one with the highest net present expected value. | The decision criterion of a cost-benefit analysis uses the summation of the effects of the expected outcomes of a project on the well-being of people within its scope. To make a summation possible, a monetary cost or benefit is assigned to each of those effects. (The term "cost-effectiveness" is a applied to an analysis in which only the costs are monetised.) The summation normally used is then the of the costs and benefits of each effect, weighted by their estimated probability of occurrence, and discounted using the estimated time preference rates of those affected. The acceptance criterion for a single project is a positive value of the resulting net present expected value of the excess of benefits over costs, and the acceptance criterion for the acceptance of one among several alternatives is that it should be the one with the highest net present expected value. | ||
===Scope=== | ===Scope=== | ||
Revision as of 15:41, 25 June 2010
Cost-benefit analysis is used to evaluate projects that generate non-financial costs and benefits by taking account of the preferences of those affected. It has applications to the provision of public goods for which preferences are not reflected in market prices. Although its quantitative results are necessarily approximate, it can sometimes provide a persuasive guide to a choice among alternatives. It is claimed that, by taking account of the strengths of preferences, cost-benefit analysis can provide a better guide to choice than can be obtained from voting.
Introduction
The problem that is tackled by cost-benefit analysis is that of making a decision on behalf of others. The objective of the decision-maker is taken to be the achievement of an outcome that those affected would have chosen in preference to all of the feasible alternatives. That objective cannot be fully achieved because the decision-maker cannot be fully aware of the preferences of others. In the pursuit of his objective, the decision-maker is nevertheless under an obligation to take account in his decision of all of the available information about those preferences.
The following paragraphs outline the methods by which that problem is normally tackled, provide examples of their application, and include an account of their limitations.
Methodology
The basic method
The decision criterion of a cost-benefit analysis uses the summation of the effects of the expected outcomes of a project on the well-being of people within its scope. To make a summation possible, a monetary cost or benefit is assigned to each of those effects. (The term "cost-effectiveness" is a applied to an analysis in which only the costs are monetised.) The summation normally used is then the of the costs and benefits of each effect, weighted by their estimated probability of occurrence, and discounted using the estimated time preference rates of those affected. The acceptance criterion for a single project is a positive value of the resulting net present expected value of the excess of benefits over costs, and the acceptance criterion for the acceptance of one among several alternatives is that it should be the one with the highest net present expected value.
Scope
The scope of an analysis is normally determined by the requirements of its prospective users. The evaluation of a medical procedure might, for example, be concerned solely with its effects on patients and their families, or it might also encompass effects on the hospital or on the public at large. An evaluation of migration commissioned by a European government might or might not be required to include effects upon migrants and their families, but an evaluation commissioned by the European Union might be expected to require the inclusion of effects upon all of its inhabitants. Some users require the coverage of a longer timescale than others, and environmental studies may even be required to encompass effects on future generations.
Reports that do not specify the scope of a quoted cost-benefit analysis are open to misinterpretation.
Measurements
The monetary value of an outcome of a project to a person is taken to be the amount that would be just sufficient to induce that person to tolerate its harmful effects or to forego its benefits.
Aggregation
Risks
Discounting
Applications
Health and safety
Transport
The environment
Climate change
Limitations
Metrics used in cost-benefit analyses
- Cost per year of life saved[1] The definition of an acceptable cost per year of life saves ranges from $50,000 to $200,000.[2]
- Cost of Preventing an Event (COPE)[3]. For example, to prevent a major vascular event n a high-risk adult , the number needed to treat is 19, the number of years of treatment are 5, and the daily cost of the generic drug is 68 cents. The COPE is 19 * 5 * ( 365 * .68) which equals $23,579 in the United States.
- Years (or months or days) of life saved. "A gain in life expectancy of a month from a preventive intervention targeted at populations at average risk and a gain of a year from a preventive intervention targeted at populations at elevated risk can both be considered large."[4]
Standards in conducting a cost-benefit analysis
Standards have been developed for the conduct of cost-benefit analyses[5][5] and for systematic reviews of cost-benefit analyses[6].
The two most common problems in publications of cost-benefit analyses are not stating the study perspective (e.g. is the cost born by the patient, health case system, or society) and not disclosing the funding source.[7]
Difficulties in cost-benefit analyses
The costs saved by successful treatment of one disease may be offset by greater longevity leading to increased costs from other disease.[8]
Recommendations have bee published on how to read and interpret a cost-benefit analysis.[9][10][11][12]
References
- ↑ Tengs TO et al (1995). "Five-hundred life-saving interventions and their cost-effectiveness". Risk Anal 15: 369–90. PMID 7604170. [e]
- ↑ Cutler DM, Rosen AB, Vijan S (2006). "The value of medical spending in the United States, 1960-2000". N. Engl. J. Med. 355 (9): 920-7. DOI:10.1056/NEJMsa054744. PMID 16943404. Research Blogging.
- ↑ Maharaj R (2008). "Adding cost to NNT: the COPE statistic". ACP J. Club 148 (1): A8. PMID 18170986. [e]
- ↑ Wright JC, Weinstein MC (1998). "Gains in life expectancy from medical interventions--standardizing data on outcomes". N Engl J Med 339: 380–6. PMID 9691106. [e]
- ↑ 5.0 5.1 Siegel JE, Weinstein MC, Russell LB, Gold MR (1996). "Recommendations for reporting cost-effectiveness analyses. Panel on Cost-Effectiveness in Health and Medicine". JAMA 276 (16): 1339–41. PMID 8861994. [e]
Cite error: Invalid
<ref>tag; name "pmid8861994" defined multiple times with different content - ↑ Jefferson T, Demicheli V, Vale L (2002). "Quality of systematic reviews of economic evaluations in health care". JAMA 287 (21): 2809-12. PMID 12038919. [e]
- ↑ Neumann PJ, Stone PW, Chapman RH, Sandberg EA, Bell CM (2000). "The quality of reporting in published cost-utility analyses, 1976-1997". Ann. Intern. Med. 132 (12): 964-72. PMID 10858180. [e]
- ↑ van Baal PH, Polder JJ, de Wit GA, et al (2008). "Lifetime Medical Costs of Obesity: Prevention No Cure for Increasing Health Expenditure". PLoS Med. 5 (2): e29. DOI:10.1371/journal.pmed.0050029. PMID 18254654. Research Blogging.
- ↑ Drummond MF, Richardson WS, O'Brien BJ, Levine M, Heyland D (1997). "Users' guides to the medical literature. XIII. How to use an article on economic analysis of clinical practice. A. Are the results of the study valid? Evidence-Based Medicine Working Group". JAMA 277 (19): 1552-7. PMID 9153371. [e]
- ↑ O'Brien BJ, Heyland D, Richardson WS, Levine M, Drummond MF (1997). "Users' guides to the medical literature. XIII. How to use an article on economic analysis of clinical practice. B. What are the results and will they help me in caring for my patients? Evidence-Based Medicine Working Group". JAMA 277 (22): 1802-6. PMID 9178794. [e]
- ↑ Greenhalgh T (1997). "How to read a paper. Papers that tell you what things cost (economic analyses)". BMJ 315 (7108): 596-9. PMID 9302961. [e]
- ↑ Detsky AS, Naglie IG (1990). "A clinician's guide to cost-effectiveness analysis". Ann. Intern. Med. 113 (2): 147-54. PMID 2113784. [e]
- ↑ Appraisal and Evaluation in Central Government, HM Treasury, 2003
- ↑ Managing risks to the public: appraisal guidance, HM Treasury, 2005