# **_Further observations on regulatory comparisons_**

Regardless of one’s take on the outcomes discussed in the preceding sections, the results demonstrate the value of _ex post_ analysis. Why, then, is it so rare, especially when so many close observers claim to be in favor of it? One answer is that it depends on what sort of _ex post_ analysis you mean. There are plenty of _ex post_ studies of policy effectiveness and overall progress at achieving policy goals. In the environmental sphere EPA closely monitors air and water quality, among other things. They also routinely conduct studies of the overall benefits and costs of programs, often retrospective studies like the benefits and costs of a clean environment, which EPA is mandated to prepare and send to Congress periodically. Some analyses are also carried out by academic researchers, such as an oft-cited paper by Greenstone (2002) on the effect of nonattainment designation on regional economic performance and air quality. Still other researchers carry out studies of the overall costs of regulations, attempting to assess the importance of regulation of various kinds relative to the economy as a whole. But these studies do not compare costs and benefits of individual regulations. Yet, it is the such uncommon _ex post_ studies that are particularly valuable for assessing the quality of regulatory processes.

One reason why there are so few _ex post_ studies of individual regulations is that there is no obvious or consistent source of funding. _Ex post_ studies are not routinely performed by regulatory agencies in the U.S. Rather, they generally appear for idiosyncratic reasons, largely dependent on the initiative of individual researchers. _Ex post_ studies also must contend, typically, with serious problems of data acquisition and interpretation. Compliance cost data are likely to be considered business confidential by regulated firms, whose participation in cost studies is often voluntary anyway. And even if the data are available, there are likely to be difficult issues of joint cost allocation. OMB’s work collecting the available _ex post_ studies is valuable, and it is to be hoped that OMB revisits the question periodically.

A related question is why certain kinds of regulations are more apt to be studied in retrospect than others. For example, in the earlier HMN survey of comparison studies (Harrington, et al. 2000, Harrington 2006), it was striking how such a large fraction of the _ex post_ studies identified were economic incentive regulations. In part, HMN interpreted this as an avuncular interest on the part of economists, who have chosen to examine these particular policies because they find them more interesting from a professional point of view. In addition, with economic incentive regulations it may be easier to get information on _ex post_ regulatory costs. For cap-and-trade programs, the marginal cost of compliance _ex post_ is equal to the permit price for every participant in the market. For emission-fee programs, the marginal compliance cost equals the unit fee, so it is the same _ex post_ as it is _ex ante_ . The total cost, of course is not quite so easy to get, since one must still estimate the cost of the infra-marginal units. Nonetheless, even total cost is much easier 16