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An Introduction to State and Local Public Finance
Thomas A. Garrett and John C. Leatherman

V. Cost-Benefit Analysis

When choosing any course of action, a person inherently performs cost-benefit analysis. The notion is one of assessing alternative available courses, anticipating the positive (benefit) and negative (cost) impacts associated with the alternatives, and selecting the course that provides the greatest net benefit. In making decisions related to public spending, the process is much the same. More formally, it is a process intended to enhance social decision-making related to the efficient allocation of scarce public resources. Typically, cost-benefit analyses (CBA) are used in the selection of alternative policies related to programs, projects or regulations.

A. Steps in Performing Cost-Benefit Analysis

Conceptually, the steps in performing a CBA are simple. Boardman, et al. (1996) list them as shown in Table 1. As might be expected,however, actually doing each step can be very difficult. Each of these steps and a few of the issues associated with completing a CBA will be discussed in greater detail in this section.

i. Identifying Stakeholders to the Analysis

The analyst begins by deciding whose costs and benefits will be counted, i.e. who has "standing." In reality, this is often determined by the project sponsor, and can be a contentious issue. The project sponsor typically is concerned about how a project will affect the sponsoring jurisdiction. Project impacts, however, often spill over space and time, causing what are often called externalities. Acid rain caused by coal-fired generators, for example, can cause problems across state and national borders. Similarly, use of fossil fuels today may preclude options for energy generation in the future.

Table 1. Basic Steps of a Cost-Benefit Analysis

1. Determine which stakeholders will be included in the analysis
2. Identify the alternative policies to be considered
3. Identify the likely physical impacts and select the appropriate measurement indicators
4. Predict the impacts over the life of the project
5. Attach a dollar amount to all of the impacts
6. Find the present value of the dollar amounts over time
7. Add up the costs and benefits
8. Perform a sensitivity analysis of the results
9. Select the alternative with the largest net social benefits

Source: Boardman, Greenberg, Vining and Weimer, 1996, page 7.


ii. Identify Alternative Policies to be Included

The alternative policies need to be evaluated relative to the status quo. Generally, a project sponsor will have well-defined alternatives in mind. But, depending how the problem is stated, the alternatives can be almost infinite. If the question is "should we build a highway?" the analysis is fairly straightforward. If the question is "how do we solve our transportation needs?" the task becomes much more complex. Generally, the project sponsors will have used other means of decision-making to narrow the choices to one or a few.

iii. Identify Likely Physical Impacts and Indicators

All of the anticipated impacts (positive and negative) need to be identified and quantified in some form. In CBA, the perspective is homocentric, i.e. from the perspective of human values. Generally, we need to know something about cause-effect relationships. In many cases, the relationships and impacts are fairly straightforward, e.g. if we build the highway, we reduce the numbers of miles traveled, we increase the time saved, reduce the lives lost, and spend so much money.

In other cases, neither the nature of the relationship nor the type of impact is readily known. Whether a given program will reduce crime, for example, is difficult to anticipate because the causal factors underpinning crime are varied and not well understood. Sometimes, we need proxy indicators for the impacts of interest, e.g. reductions in the number of convictions as opposed to reduced crime. Similarly, if an animal species is generally considered an indicator of the health of an ecosystem, valuing a reduction of ecosystem viability is a difficult task. There are times people will look at the same information and interpret it in exactly opposite ways.

iv. Predict the Impacts over the Life of the Project

Most public projects will extend over a period of time. The next task is to quantify the impacts over the life of the project and beyond if residual effects are expected. Here again, our ability to predict the future is at question. Most of the texts on CBA discuss relationships in theoretical or hypothetical terms, but very few studies of how well a CBA actually anticipates the future impacts have been performed. Some of the common errors in performing CBA’s are identified later in this section.

v. Monetize All of the Impacts

A dollar amount needs to be assigned to all of the anticipated impacts. The challenge is valuing impacts that are intuitively important but for which there are no markets or only poorly functioning markets to observe. Environmental impacts and impacts to human health and well-being are two cases in point.

vi. Find the Present Value of Dollar Amounts

For any project that extends over a period of years, all dollar amounts assigned need to be converted into a common metric. Future costs and benefits need to be discounted to obtain a present value . This is done to compare our choice of consuming resources now versus deferring that consumption to some future time. Given our assumption the CBA applies to public decision-making, we need to establish a social discount rate . Here again, determining the aggregate value all of a jurisdiction’s affected citizens place on current versus future consumption is very difficult. While there are a number of theoretical considerations that can be brought to bear on the question, there is no agreement on what social discount rate should be applied for a given type of project. For this reason, we generally present results subject to a sensitivity analysis to demonstrate how alternative discount rates affect valuation.

vii. Add up the Costs and Benefits

The basic decision rule for CBA is simple. In the case of a single project, add up the net present value of the costs and benefits and, if the benefits minus the costs are greater than zero, go ahead with the project. If two or more project alternatives are being considered, select the one with the higher positive net present value.

Some advocate using alternative criterion for the decision rule. Sometimes results are reported as an internal rate of return or a benefit-cost ratio . Both the internal rate of return and the benefit-cost ratio can lead to erroneous conclusions, however, while use of the net present value of social benefits always yields a correct answer. Where disagreements typically arise is whether all the social costs and benefits have been monetized and summed. In cases where it is not possible to reach agreements about the value of a benefit or cost, it may be appropriate to use an alternative analysis method such as a cost-effectiveness analysis .

viii. Perform a Sensitivity Analysis

The use of sensitivity analysis in the context of CBA is to deal with uncertainties. A sensitivity analysis simply means inserting alternatives from a range of values related to unknown or uncertain parameters. For example, if it is uncertain how many lives an intervention will save, a range of numbers can be entered and compared to the cost. Any number of CBA components can be subject to sensitivity analysis, including who has standing and with what weight, the social discount rate used, or any of the parameters where there is uncertainty or disagreement.

ix. Select the Preferred Alternative

Finally, the analyst recommends the alternative with the highest positive net present value of social benefits. It should be kept in mind this is a normative judgement based on an efficiency consideration. Thus, in the political process of policy choices, decision-makers may choose other alternatives. Here, the analyst is best advised to present a recommendation rather than a decision.

B. Theoretical Foundations in Cost-Benefit Analysis

There are a number of concepts that help guide the analyst in performing CBA. In this section, we explore some of the basic assumptions inherent in this type of analysis, including allocative efficiency, willingness-to-pay, and opportunity costs. Thus far, we have referred to CBA as a means to identify the most efficient alternative policy or project. Here, we discuss what we mean by efficiency in the allocation of resources with a few basic concepts from welfare economics.

A simple and compelling concept in welfare economics is the notion of Pareto efficiency . An allocation of goods is said to be efficient if no alternative allocation scheme will make at least one person better off without making anyone else worse off. Intuitively, this would be the best alternative in social decision-making, even if in practice this would be extremely difficult to know. Thus, we equate the notion of the highest net present value with Pareto efficiency by use of two related concepts: willingness-to-pay and opportunity costs.


Willingness-to-pay is the amount of money a person would be willing to pay to get or avoid something other than the status quo. The aggregation of all stakeholder’s willingness-to-pay is what is sought in identifying the net benefits of the policy. If someone were made worse off as the result of the change, we can introduce the notion of compensation to bring them back to at least the same level of well-being even if others’ well-being was improved as a result of the policy. If, after performing the analysis, there are any estimated net benefits, this would imply that the proposed change would be a Pareto improvement over the status quo.

In valuing costs and benefits, the notion of opportunity costs is critical. The opportunity cost of using a resource is the cost of not using a resource in its next best alternative use. This is functionally what has to be given up to pursue the policy of interest. If the aggregate opportunity costs exceed the aggregate willingness-to-pay of stakeholders, the net benefits would be less than zero and the policy would not be a Pareto improvement.

Using these concepts, we would suggest that if all impacts were measured as an aggregate willingness-to-pay, and all resources used as inputs into the policy were valued as opportunity costs, an analysis showing a net present value would imply that it was at least theoretically possible to compensate those who had to give something up with policy implementation and still make someone better off. Thus, the policy change would be Pareto efficient. In practice, we apply this rule by suggesting we adopt only policies that have positive net present benefits. When one policy affects another, we would seek the combination of policies with highest net benefits. When policies are mutually exclusive, we choose the one with the highest net benefits.

C. Net Present Value

Many public programs are implemented over the course of years. Taking time into account when we estimate the value of costs and benefits associated with a project is essential. Not only are we concerned about the effects of inflation, time also influences how we perceive the value of money. Discounting is fundamental to CBA, and calculating the correct discount rate can make all the difference in the outcome of an analysis. We discount future values to determine a net present value .

The net present value criterion suggests proceeding with the project if the net present value is positive if the alternative is the status quo, or to proceed with the project alternative with the largest net present value.

Thus far, we have been ignoring the effects of inflation; we have only considered the time value of money. Of course, the purchasing power of money declines over time with price inflation. The question arises as to whether it is best to express the financial information presented in nominal dollars or in inflation-adjusted real dollars.

While some analysts use nominal dollars in CBA, in public sector financial analysis it is probably best to express the information in real dollars. The financial information to be dealt with is usually more intuitively clear when expressed in real terms. When working with real dollars, however, it the becomes necessary to apply a real discount rate rather than a nominal discount rate.

Because of uncertainties related to what discount rate to apply, and because the discount rate chosen can have a substantial affect on the outcome of a CBA, it is generally appropriate to subject the discount rate to a sensitivity analysis by varying it within a range of values.

D. Estimating Values

In many cases, estimating the values of costs or benefits is fairly straight-forward. Project expediters can estimate construction costs with a great deal of accuracy, notable exceptions on some public projects notwithstanding. Similarly, we can infer a great deal where we can make direct observations of behavior in undistorted private markets. Many times, however, directly observable behavior is not readily available. Further, there are no markets for many goods, such as pollution, or the markets are imperfect. This section provides an introductory discussion of some concepts, methods, and issues associated with establishing values for costs and benefits.

i. Social Surplus

In the private sector, a reasonable measure of benefit to a producer is simply net profit. The producer deducts from gross sales the cost of goods sold plus taxes. The money remaining after paying these bills would be considered the "surplus" to the producer. This surplus has a value – the profit. It is measurable, meaningful, and can be aggregated across many producers. Thus, we equate the notion of a cost or benefit in terms of changes in surplus, all of which can be conceptually linked to the notion of willingness-to-pay. In this case, for the opportunity to change the producer’s "surplus," his willingness to pay would be exactly equal to the amount of the profit.

For public projects, valuing costs and benefits is not so simple. To the extent a project affects private producers, the analyst would be interested in measuring changes in producer surplus. But, public projects are often intended to benefit consumers (citizens), as well. To the extent a project benefits non-producers, we are also interested in measuring consumer surplus. The CBA attempts to capture changes for both groups. Together, the sum of producer and consumer surplus is social surplus , and this concept is what the analyst is trying to measure.


If there existed perfect markets for all goods and services, and supply and demand curves were known, measuring social surplus would be easy. Unfortunately, markets do not always work perfectly, for many types of goods markets do not exist, and we seldom have sufficient information to accurately depict supply and demand curves. Thus, we use a variety of methods to approximate markets to estimate supply and demand.

ii. Estimating Values in Cost-Benefit Analysis

There are a variety of methods to estimate the values of costs and benefits associated with public projects. Sometimes, a demonstration project or social experiment is conducted, studied and extrapolated to a larger initiative. In other cases, costs are estimated based on observations, or inferred from survey information or secondary data sources. This section will explore several of the basic methods used for estimating values in CBA.

a. Values from Observed Behavior

There are a number of practical methods available to estimate values based on observable behavior. These methods focus principally on changes in consumer surplus. Several are briefly outlined in this section.

1. Project Revenues as Benefits

In the private sector, counting revenues generated by a project as benefits makes sense. Project revenues may undercount the value of the benefits of public projects, however, because they do not consider changes in social surplus. In the example of introducing electricity to a remote area, we would grossly undervalue benefits if we only counted government-subsidized rates. Clearly, residents of the area would experience benefits beyond the fees generated if the alternative was no electricity. Project revenues, therefore, are not always a good indicator of benefit.

2. Estimating Demand Curves

If we have information about the quantity of a good demanded at different prices, it may be possible to make a direct estimation of the consumer demand curve (Barnett, 1988). For example, if we have data related to changes in bus ridership at various fare rates, we have all the information needed to estimate the consumer demand curve using econometrics – price of the service, quantity of rides demanded, the elasticity of demand at various prices. We can extrapolate from the available data the marginal benefit to the consumer of the service at a given price with a reasonable degree of confidence.

3. Market Analogy

For many public goods and services, there is no well-functioning market. Public education, recreational facilities, and many types of health services are cases in point. We can look for a private sector equivalent to extrapolate to the public sector, such as observing the prices paid at private universities, private camp sites, or private health care providers. Sometimes, it may even be possible to use information gathered from informal (illegal) markets when no legal private market exists.

4. Intermediate Goods

Governments sometimes produce goods that are used as inputs into production. An agricultural irrigation project is a good example. In a reasonably well-functioning agricultural commodities market, we can observe the incomes of dry-land versus irrigated farming producers. After taking into account the relative differences in input costs, we can reasonably estimate the "value added" to agricultural production associated with the government irrigation project.

5. Asset Values

Government projects can sometimes affect the price of assets such as land and capital. Once again, agriculture is a good case to illustrate this point. Land values will be quite different between land having access to irrigation water and land without. Similarly, differences in the market value of comparable homes near an airport versus those more distant can provide an indication of the value of a negative externality such as noise.

6. Hedonic Pricing

Building on the methods previously outlined, hedonic price functions use a regression method to value attributes that affect asset values, such as the value of a scenic vista in a housing market (Rosen, 1974). The method would first estimate the additional value of a house with a marginally better view, holding other factors that affect values constant. Secondly, willingness-to-pay is estimated, controlling for income and other socioeconomic factors. Using this method, consumer surplus can be estimated for projects that might improve or worsen a scenic vista.

7. Travel Cost Method

The travel cost method recognizes that the fees generated by an event or facility are only a small part of a consumers’ willingness-to-pay. To enjoy the experience of a visit to a national park, for example, people will forego the opportunity to work, travel great distances, and incur significant food and lodging expenses. Thus, the value of the experience will exceed the gate admission many times over. The travel cost method uses the total cost of the trip, instead of the admission price, as an explanatory variable in estimating demand. As might be expected, this method is most often used in recreation-related studies.

8. Defensive Expenditures

Many people are willing to take defensive action in response to a situation (Bartik, 1988). For example, people will install home water purification systems or purchase bottled water in response to concerns related to water quality. If government takes action to maintain or improve water quality, some people will forego the expense they previously incurred. We can value water quality by observing the full costs incurred to take defensive action, and the value of government intervention by observing the changes in defensive behavior.

b. Contingent Valuation

Sometimes, there are no markets or proxies available with which to infer a value. In such instances it may be necessary to elicit people’s perceptions of value using survey methods. The survey methods used in CBA are referred to as contingent valuation.

There are a number of survey techniques available to elicit people’s estimates of value (Bishop and Heberline, 1990; Cummings, et al., 1986). Open-ended questionnaires will simply ask how much a person would be willing to pay for a good. Closed-ended iterative bidding surveys specify a specific but variable amount and inquire whether a person would be willing to pay it. A third type of survey will ask people to rank order specific combinations of quantities of a good and associated payments. The dichotomous-choice method randomly assigns a price to a given quantity of a good, and people are asked whether they would be willing to pay the amount. Finally, there are several variations of the payment card method where people indicate a willingness to pay based on comparable goods or based on the hypothetical maximum amount they would pay. All of these approaches have been used with in-person interviews, telephone surveys and mail surveys (Mitchell and Carson, 1989).

As with all survey techniques, contingent valuation methods are subject to a number of potential problems (Hausman, 1993; Arrow, et al., 1993), including sample bias, non-response bias, and interviewer bias. In addition, contingent valuation methods have been criticized as being inaccurate in establishing a true willingness-to-pay. One of the principal criticisms is that a person’s response to a hypothetical situation may be quite different than their response if faced with the reality of actually having to pay. Similarly, it can be very difficult to establish a meaningful context for the provision of a public good. A person would be willing to pay very different amounts to cross a bridge to go to a movie versus getting to a hospital emergency room.

Contingent valuation methods are frequently used in valuing environmental resources (Bateman and Willis, 1999). In this application, it has proven difficult to establish a context for questioning that people with differing views agree is neutral.

Given the hypothetical nature of the situations described in contingent valuation surveys, there have also been concerns related to respondents’ inability to adjust their views by learning. We may think we value a good accurately, but may change that view after having had experience in its actual consumption. In marketing, it is well known that people tend to overvalue items with which they have had no prior experience.

There are a number of other criticisms related to contingent valuation methods. Each of the survey techniques has inherent strengths and weaknesses. In general, there is less criticism of contingent valuation methods when the survey is conducted while the respondent is actually engaged in the behavior of interest, as when recreating. Conversely, there is a great deal of controversy associated with studies that employ "non-use" or hypothetical situations. Clearly, a great deal of care is needed to conduct valid contingent valuation studies.

c. Shadow Prices

As the previous sections imply, conducting a CBA can be complex, costly, and time consuming. Whatever can be done to simplify and speed up completion of the study is generally accepted. Thus, many analysts adapt the results of previous research for use in CBA. Using values associated with preexisting studies is referred to as using shadow prices . A considerable amount of work has been conducted in three areas where it would otherwise be very difficult to estimate a value: the value of life , the value of time , and the negative values associated with particular crimes .

The table from Boardman et al. 1996, summarizes the results of major work in establishing various shadow prices frequently used in CBA. The wide variance of the values reported in the studies represented suggest the difficulty and imprecision with which we are currently able to establish such values.

E. Common Errors in Cost-Benefit Analyses

Invariably, errors occur when the task is to predict the future. Yet, there is considerable benefit in trying to anticipate the likely consequences of alternative courses of action in a rigorous fashion. It is legitimate to question how good our CBA methods actually perform. Few have taken the effort to compare CBA predictions with the actual outcomes. Despite the paucity of evidence, we can identify some of the common errors that have been observed in CBA (Boardman, et al.,1996; Rosen, 1985).

i. Errors of Omission

Errors of omission can arise from several sources. The first may be with whose interests we are concerned. Without adequate consideration or concern about who is affected by externalities, both costs and benefits may be undercounted. Similarly, some potential impacts may be considered either so remote or uncertain they are not counted at all. Such may be the case with industry air quality regulations and global warming.

ii. Forecasting Errors

There are a host of difficulties in forecasting future events. Generally, as the complexity of the project and the time horizon of the forecast increases, errors are more likely. Anticipating the rate of technical change or comprehending cause-effect relationships make forecasting difficult. Similarly, when the project is large, it is not uncommon for specifications to evolve over time.

iii. Measurement Errors

Even measuring events in the present is subject to the limitations of our measuring devices, the accuracy with which they are used, and our capacity to statistically analyze and interpret results. It is easy to forget the limitations of our primary data-gathering techniques and secondary data sources, and then further compound errors though data analysis.

iv. Valuation Errors

As indicated in earlier sections, the capacity to generate values associated with impacts is difficult and imprecise. Many of our measurement techniques are problematic, and their use is sometimes flawed. Similarly, the stock of available information related to shadow prices is relatively scarce. The range of values calculated across studies and methods attests to the imprecision of our current knowledge.

v. Indirect Impacts

In some cases, indirect economic impacts are counted as additional benefits, while indirect costs are ignored. If there is an effort to trace secondary and other tertiary impacts on the positive side to enhance the benefits, a similar effort is needed to trace the costs. In most cases, the effects are offsetting without a significant change in the net result (Rosen, 1985).

vi. Double-Counting

Double-counting is the opposite of the error by omission. Here, too many impacts are counted. In the case where a project both increases the value of land and the income generated by farming it, both should not be counted. In a competitive market, the value of the land is equal to the present value of the income generated by farming it. Counting increased land value and increased farm income represents double-counting.

vii. The Value of Labor

The value of labor associated with a government-funded project, such as road building, is sometimes counted as a benefit. The labor purchased with public funding should be considered a cost to the project, unless the new labor was formerly from the ranks of the long-term unemployed.

F. Conclusion

The utility of cost-benefit analysis is that it introduces the notion of comprehensively accounting for the positive and negative impacts associated with public projects. It introduces a methodology that fosters rigor in thinking. Clearly, this represents an improvement over much state and local policy-making that is based on supposition and ideology.

The techniques associated with CBA are far from perfect, but there continue to be advances in technique and application. Still, it remains the responsibility of the analyst to employ the theory and techniques in a conscientious manner and help policy-makers understand the full impact of the decisions made. Even if applied in only a partial fashion, cost-benefit analysis can help state and local government officials improve the quality of decision-making.


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