diversifying external linkages the exercise of irish economic sovereignty in long term perspective political independence is usually associated with an attempt to reduce economic dependency on the former dominant or colonial power for most of the early period since irish independence the attempt to reduce exposure to the uk was implemented through tariff protection and restrictions on foreign ownership inward orientation eventually ran out of steam culminating in sustained emigration and deep recession in the 1950s the genesis in the mid 1950s of ireland s low corporation tax regime facilitated later trade liberalization and diversified the economy away from the uk these developments facilitated the full convergence on uk and broader western european living standards that was eventually achieved in the 1990s from 1979 the uk would diverge from most of the rest of western europe on exchange rate policy and ireland was forced to choose between the two the resulting difficulties can be ascribed to design flaws in the european monetary project and ireland s failure to recognize the constraints that the new regime imposed

bankable permits for the control of environmental pollution abstract intertemporal trading of emission permits banking is often identified as one of three promising market mechanisms for controlling pollution along with averaging and trading surprisingly the efficiency properties of permit banking systems have not been investigated using a simple optimal control model this paper investigates firms incentives for banking or borrowing emission permits and compares the emission and output streams firms would choose with the socially optimal solution we find that in many cases firms will suboptimally choose excessive damage and output levels in early periods and correspondingly too few in later periods if given the opportunity to freely move emissions between time periods we propose a simple alternative trading scheme we term modified banking that counters this problem and should be no more difficult for an environmental authority to implement than a straigth banking system

unemployment growth and taxation in industrial countries unemployeement and taxes do taxes affect the rate of umemployeement to the layman the upward trend in european unemployment is related to the slowdown of economic growth we argue that the layman s view is correct the increase in european unemployment and the slowdown in economic growth are related because they stem from a common cause an excessively rapid growth in the cost of labour in europe labour costs have gone up for many reasons but one is particularly easy to identify higher taxes on labour if wages are set by strong and decentralized trade unions an increase in labour taxes is shifted onto higher real wages this has two effects first it reduces labour demand and thus creates unemployment secondly as firms substitute capital for labour the marginal product of capital falls over long periods of time this in turn diminishes the incentive to invest and to grow the data strongly support this view according to our estimates the observed rise of 14 percentage points in labour tax rates between 1965 and 1995 in the eu could account for a rise in eu unemployment of roughly 4 percentage points a reduction of the investment share of output of about 3 percentage points and a growth slowdown of about 0 4 percentage points a year francesco daveri and guido tabellini

strategic responses to automobile emissions control a game theoretic analysis abstract this paper examines the dynamics of standard setting regulation under technological uncertainty and asymmetric information about technological capability a two period model which allows fully strategic action is developed and applied to the regulation of automobile emissions a situation in which standards have been used to force innovation it is found that the initial level of r d activity caused by regulation increases with the intrinsic technical capability of industry this result done not depend on marginal productivities of research that favor high capability types and implies that a poor capability industry will not attempt to compensate for its inability to innovate with increased research activity it is also found that the regulator s ability to induce investment is greater when r d is likely to be unsuccessful

planning under incomplete information and the ratchet effect abstract central planning of production is usually performed under asymmetric information the firm in general has more information about its productive possibilities than the central planner from now on for short cp this justifies the use of incentives schemes in which the cp does not directly fix activity levels casual observation of such existing schemes suggests that the time dimensions is crucial for their working typically the cp revises the incentive scheme over time to take into account the information provided by the firm s performance managers of centrally planned economies as well as economists have long recognized that this revision induces firms to underproduce in order to avoid demanding schemes in the future this is the ratchet effect it is purpose of the present paper to study the ratchet effect under the non commitment assumption which we believe to be more realistic the inadequacy of conceptual tools made if difficult in the past to consider such an assumption now basic research on dynamic games with incomplete information recently resulted in new ideas which look particularly relevant for a theoretical analysis of the problem

regulating stock externalities under uncertainty abstract using a simple analytical model incorporating benefits of a stock costs of adjusting the stock and uncertainty in costs we uncover several important principles governing the choice of price based policies e g taxes relative to quantity based policies e g tradable permits for controlling stock externalities as in weitzman rev econom stud 41 4 1974 477 the relative slopes of the marginal benefits and costs of controlling the externality continue to be critical determinants of the efficiency of prices relative to quantities with flatter marginal benefits and steeper marginal costs favoring prices but some important adjustments for dynamic effects are necessary including correlation of cost shocks across time discounting stock decay and the rate of benefits growth applied to the problem of greenhouse gases and climate change we find that a price based instrument generates several times the expected net benefits of a quantity instrument

elicitation format and sensitivity to scope this paper undertakes a systematiccomparison of the contingent valuation cv andchoice experiments ce methods andinvestigates the extent to which either of themare affected by insensitivity to scope this isachieved by undertaking separate cv estimatesof willingness to pay for two nested publicgoods both of which are explicitly included ina parallel ce survey the results indicate thatce values exhibit greater sensitivity to scopethan cv values ce gives significantly largerresults than cv for the more inclusive publicgood and significantly smaller results for theless inclusive public good

commitment and fairness in a dynamic regulatory relationship this paper considers a multiperiod model of a regulated firm that has stationary private information which may be revealed through performance if it cannot make commitments to future policies the regulator has an incentive to exploit any information the firm reveals and laffont and tirole show that there is no regulatory policy that is separating over any closed interval a fairness arrangement is proposed in which the firm agrees not to quit if in future periods the regulator allows it to earn a nonnegative profit given the type it revealed in earlier periods the properties of such arrangements are studied and an example is presented in which both the firm and the regulator prefer a fairness arrangement to a policy feasible without commitment

to what extent were economic factors important in the separation of the south of ireland from the united kingdom and what was the economic impact the impact of british rule casts a long shadow over irish history while nationalist historians tended to blame union with britain for all the economic ills of the 19th century o brien 1921 recent re evaluations of both historical and recent irish economic performance have been cause for a reappraisal of the economic relations between ireland and britain cullen 1969 kennedy and johnson 1996 the extent to which economic factors were important in ireland s withdrawal from the united kingdom will be examined in this paper a secondary aim is to assess the economic consequences of independence in the interwar period there were many economic reasons up to 1913 as to why ireland should separate uk policy was determined by majority voting and policies were suited to the needs of industrial workers in britain rather than agricultural workers in ireland this led to increased spending beyond the means of ireland which caused transition difficulties on independence finally the consequences of separation in the north and south of ireland are examined evidence suggests that separation led to short term economic difficulty in the longer run the south benefited from independence due to weakness in british institutions and the incentive structures created during the interwar period

renegotiation of concession contracts in latin america evidence from the water and transport sectors abstract high rates of contract renegotiation have raised serious questions about the viability of the concession model to attract private participation in infrastructure in developing countries after extending in reduced form a standard regulation model in which renegotiation occurs due to the imperfect enforcement of concession contracts we use a unique data set of 307 concessions awarded in latin america from 1989 to 2000 covering the sectors of transport and water to analyze the determinants of this high incidence of renegotiations of infrastructure contracts we look in details at the impact on the probability of renegotiation of a concession of regulatory institutions institutional features economic shocks and of the characteristics of the concession contracts themselves we then derive some policy implications of our work

treatment of don t know responses in contingent valuation surveys a random valuation model abstract this paper provides a utility theoretic interpretation of don t know dk responses in contingent valuation surveys using a referendum elicitation procedure the random valuation model in this paper assumes that each respondent of a contingent valuation survey has an implicit valuation distribution rather than a single true value as traditionally assumed in his her mind if an offered referendum bid is not clearly different from the mean value of one s valuation distribution the respondent may give a dk answer to the cv referendum question based on this model a maximum likelihood procedure is proposed for estimating respondents willingness to pay for a nonmarket good with referendum contingent valuation data which include dk responses an empirical illustration of this estimation procedure is also provided

a satisfactory benefit cost indicator from contingent valuation abstract standard economic concepts are used to develop a model of individual behavior when subject to the constraints of the contingent valuation choice context the model yields refutable consequences that are consistent with previously reported empirical findings including some that have been thought to be anomalous the model is used to show that different contingent valuation formats have predictably different performance characteristics notably the hicksian compensating measures are satisfactory benefit cost indicators when elicited using any one of several formats identified in the text of the formats examined one form of a policy referendum appears to have the most satisfactory characteristics overall we conclude that contingent valuation is a progressing research program

optimal environmental regulation under asymmetric information abstract a market model of environmental regulation with interdependent production and pollution abatement costs and heterogeneous firms is developed firms have private information about costs which have a quadratic form firms pursue bayes nash strategies in communication with the regulator the full information optimum cannot be attained unless gains from trade in the product market net of external damages exceed the information rents earned by firms aggregate output and externality levels are lower at the regulated equilibrium than at the full information social optimum

correlated uncertainty and policy instrument choice abstract for two decades environmental economists have generally maintained that benefit uncertainty is irrelevant for choosing between price and quantity instruments but that cost uncertainty matters with the identity of the efficient instrument depending upon the relative slopes of the marginal benefit and cost functions but in the presence of simultaneous correlated uncertainty such policy instrument recommendations may be inappropriate with plausible values of relevant parameters the conventional identification of a price instrument will be reversed to favor instead a quantity instrument the opposite reversal from the choice of a quantity instrument to a price instrument seems less likely to occur

substitution effects in the valuation of multiple environmental programs abstract a theoretical framework for understanding substitution and complementary effects between environmental programs is derived a multiple program valuation function is specified and its structure analyzed a maximum likelihood estimator is derived to estimate the parameters of the valuation function using referendum type contingent valuation data the empirical analysis shows that the conventional benefit aggregation approach of independent valuation and summation overstates the benefits of two and three program policies by an average of 24 and 54 respectively

a simple auction mechanism for the optimal allocation of the commons efficient regulation of the commons requires information about the regulated firms that is rarely available to regulators e g cost of pollution abatement this paper proposes a simple mechanism that implements the first best for any number of firms a uniform price sealed bid auction of an endogenous number of transferable licenses with a fraction of the auction revenues given back to firms paybacks which rapidly decrease with the number of firms are such that truth telling is a dominant strategy regardless of whether firms behave non cooperatively or collusively the mechanism also provides firms with incentives to invest in socially optimal r d jel d44 d62 d82 q28 regulatory authorities generally find that part of the information they need for implementing an efficient regulation is in the hands of those who are to be regulated regulating externalities such as access to common resources e g clean air water streams fisheries etc is a good example environmental regulators for example know little about firms pollution abatement costs so without communicating with firms they would be unable to establish the efficient level of pollution a number of mechanisms have been proposed for inducing firms to reveal their private information but for different reasons

measuring the difference in mean willingness to pay when dichotomous choice contingent valuation responses are not independent dichotomous choice contingent valuation surveys frequently elicit multiple values in a single questionnaire if individual responses are correlated across scenarios the standard approach of estimating willingness to pay wtp functions independently for each scenario may result in biased estimates of the significance of the difference in mean wtp values this paper applies an alternative bivariate probit approach that explicitly accounts for correlation across errors in the estimation of wtp and mean wtp using data from three separate dichotomous choice contingent valuation studies this correlation is demonstrated to have an effect on the significance level of mean wtp difference tests

confidence intervals for evaluating benefits estimates from dichotomous choice contingent valuation studies i evaluate the potential usefulness of nonmarket valuation concepts and techniques from environmental economics for improving wildlife conservation the concepts include distinguishing between on site recreation use value and off site passive use or

the additionality problem with offsets optimal contracts for carbon sequestration in forests abstract carbon offsets are a frequently discussed tool for reducing the costs of an emissions reduction policy however offsets have a basic problem stemming from asymmetric information sellers of offsets have private information about their opportunity costs leading to concerns about whether offsets are additional non additional offsets can undermine a cap and trade program or if the government purchases them directly result in enormous government expenditures we analyze contracts for carbon sequestration in forests that mitigate the asymmetric information problem landowners are offered a menu of two part contracts that induces them to reveal their type under this scheme the government is able to identify ex post how much additional forest each landowner contributes and minimize ex ante its expenditures on carbon sequestration to explore the performance of the contracting scheme we conduct a national scale simulation using an econometric model of land use change the results indicate that for an increase in forest area of 61 million acres government expenditures are 5 3 billion lower under the contracting approach compared to a uniform subsidy offered to all landowners this compares to an increase in private opportunity costs of just 110 million dollars under the contracts thus the contracting scheme is preferable from society s perspective

inward investment and irish exports over the recession and beyond with the collapse in domestic demand the performance of ireland s export sectors will remain key to the stabilisation of the economy the paper analyses the performance of irish exports in internationally comparative terms and assesses the contributions of both foreign affiliate and indigenous firms across both manufacturing and services since almost 80 per cent of irish exports are generated by foreign affiliates medium term export prospects are highly dependent on trends and developments in global market conditions for foreign direct investment the paper discusses the likely impact on the country s medium term prospects of technological developments in key sectors and possible changes in the international regulatory and corporation tax landscapes

a solution to the problem of externalities when agents are well informed the author describes a class of simple two stage mechanisms that implement efficient allocations as subgame perfect equilibria for economic environments involving externalities these mechanisms known as compensation mechanisms solve a wide variety of externalities problems including implementation of lindahl allocations regulation of monopoly and efficient solutions to the prisoner s dilemma copyright 1994 by american economic association

the political economy of market based environmental policy the u s acid rain program the u s acid rain program enacted in 1990 gave valuable tradable sulfur dioxide emissions permits called allowances to electric utilities we examine the political economy of this allocation though no senate or house votes were ever taken hypothetical votes suggest that the actual allocation would have beaten plausible alternatives while rent seeking behavior is apparent statistical analysis of differences between actual and benchmark allocations indicates that the legislative process was more complex than simple models suggest the coalition of states that produced and burned high sulfur coal both failed to block acid rain legislation in 1990 and received fewer allowances than in plausible benchmark allocations some of these states may have received additional allowances to cover 1995 99 emissions by giving up allowances in later years and some major coal producing states seem to have focused on benefits for miners and on sustaining demand for high sulfur coal

economic prescriptions for environmental problems how the patient followed the doctor s orders o ne of the dangers with ivory tower theorizing is that it is easy to lose sight of the actual set of problems which need to be solved and the range of potential solutions as one who frequently engages in this exercise i can attest to this fact in my view this loss of sight has become increasingly evident in the theoretical structure underlying environmental economics which often emphasizes elegance at the expense of realism in this paper i will argue that both normative and positive theorizing could greatly benefit from a careful examination of the results of recent innovative approaches to environmental management the particular set of policies examined here involves two tools which have received widespread support from the economics community marketable permits and emission charges pigou 1932 dales 1968 kneese and schultze 1975 both tools represent ways to induce businesses to search for lower cost methods of achieving environmental standards they stand in stark contrast to the predominant command and control approach in which a regulator specifies the technology a firm must use to comply with regulations under highly restrictive conditions it can be shown that both of the economic approaches share the desirable feature that any gains in environmental quality will be obtained at the lowest possible cost baumol and oates 1975 until the 1960s these tools only existed on blackboards and in academic journals as products of the fertile imaginations of academics however some countries have recently begun to explore using these tools as part of a broader strategy for managing environmental problems

regulation of stock externalities with correlated abatement costs we study a dynamic regulation model where firms actions contribute to a stock externality the regulator and firms have asymmetric information about serially correlated abatement costs with price based policies such as taxes or if firms trade quotas efficiently the regulator learns about the evolution of both the stock and costs this ability to learn about costs is important in determining the ranking of taxes and quotas and in determining the value of a feedback rather than an open loop policy for a range of parameter values commonly used in global warming studies taxes dominate quotas regardless of whether the regulator uses an open loop or a feedback policy and regardless of the extent of cost correlation

emission taxes and optimal refunding schemes abstract we examine how refunding emission taxes to firms dependent on market shares should be designed while refunding is harmful under perfect competition a first best self financing tax tax refunding scheme exists if the marginal damage from pollution exceeds the marginal distortion in an imperfectly competitive output market with symmetric firms under pre investment in cleaner technology with short term abatement opportunities a first best refunding scheme exists if pollution refunding can be made dependent on both market and investment shares

oil field unitization contractual failure in the presence of imperfect information an empirical analysis of the impact of transaction costs on contracting shows that imperfect in formation can seriously limit the effectiveness of private contracting the case under study is the widespread failure of private crude oil producing firms to use us oil fields to reduce rent dissipation rent dissipation follows as multiple firms compete for migratory oil in common oil pools unitization is the obvious private contractual solution to rent dissipation the authors argue that despite large net gains from unitization imperfect information and information asymmetries among the negotiating parties regarding lease values prevents consensus on unit shares as a result contracts are often not completed or only fragmented units are completed 9 references 1 figure 4 tables

choice modelling approaches a superior alternative for environmental valuation in this paper we examine some popular choice modelling approaches to environmental valuation which can be considered as alternatives to more familiar valuation techniques based on stated preferences such as the contingent valuation method a number of choice modelling methods are consistent with consumer theory and its focus on an attribute based theory of value permits a superior representation of many environmental management contexts however choice modelling surveys can place a severe cognitive burden upon respondents and induce satisficing rather than maximising behavioural patterns in this framework we seek to identify the best available choice modelling alternative and investigate its potential to solve some of the major biases associated with standard contingent valuation we then discuss its use in the light of policy appraisal needs within the eu an application to the demand for rock climbing in scotland is provided as an illustration

dynamic regulation design without payments the importance of timing abstract we consider a two period model of optimal regulation of a firm subject to marginal compliance cost shocks the regulator faces an asymmetric information problem the firm knows current compliance costs but the regulator does not both the regulator and the firm are uncertain about future costs in our basic framework the regulator may not offer payments to the firm we show that the regulator can vary the strength of regulation over time to induce the firm to reveal its costs and increase welfare in the optimal mechanism the regulator offers stronger weaker regulation in the first period and weaker stronger regulation in the second period if the firm reports low high compliance costs in the first period low cost firms expect compliance costs to rise in the future and thus prefer weaker regulation in the second period high cost firms expect costs to fall in the future and thus prefer regulation which becomes stricter over time thus the regulator offers the low high cost firms slightly weaker stronger regulation in the second period in exchange for much stronger weaker regulation in the first period thereby timing the regulation if the regulator can make payments then the optimal mechanism to some degree times the regulation as long as a positive marginal cost of funds exists if the marginal cost of funds is high enough then under the optimal mechanism the regulator will not use payments and use our timing mechanism exclusively

scotland and small country independence the assessment this paper reviews some of the issues consequent on the formation of new states through secession while its particular focus relates to the potential withdrawal of scotland from the united kingdom it discusses preference heterogeneity as a potential cause of the break up of states relating that to recent developments in the economics of identity it examines some macroeconomic issues particularly debt and currency and reflects on how these might influence secession it examines alternatives fiscal decentralization to secession and considers the strategies that those arguing for and against secession may deploy it also explains the structure of this issue explaining how the different contributions come together

optimal environmental taxation in the presence of other taxes general equilibrium analyses this paper examines the optimal setting of environmental taxes in economies where other distortionary taxes are present we employ analytical and numerical models to explore the degree to which in a second best economy optimal environmental tax rates differ from the rates implied by the pigovian principle according to which the optimal tax rate equals the marginal environmental damages both models indicate contrary to what several analysts have suggested that the optimal tax rate on emissions of a given pollutant is generally less than the rate supported by the pigovian principle moreover the optimal rate is lower the larger are the distortions posed by ordinary taxes numerical results indicate that previous studies may have seriously overstated the size of the optimal carbon tax by disregarding pre existing taxes this abstract was borrowed from another version of this item

emissions targets and the real business cycle intensity targets versus caps or taxes for reducing greenhouse gas emissions intensity targets are attracting interest as a flexible mechanism that would better allow for economic growth than emissions caps for the same expected emissions however the economic responses to unexpected productivity shocks differ using a real business cycle model we find that a cap dampens the effects of productivity shocks in the economy on all variables except for the shadow value of the emissions constraint an emissions tax leads to the same expected outcomes as a cap but with greater volatility certainty equivalent intensity targets maintain higher levels of labor capital and output than other policies with lower expected costs and no more volatility than with no policy

what drives the german current account and how does it affect other eu member states we estimate a three country model using 1995 2013 data for germany the rest of the euro area rea and the rest of the world row to analyse the determinants of germany s current account ca surplus after the launch of the euro our results suggest that the german surplus reflects a succession of distinct shocks mono causal explanations of the surplus are thus insufficient the most important factors driving the german surplus were positive shocks to the german saving rate and to row demand for german exports as well as german labour market reforms and other positive german aggregate supply shocks the key shocks that drove the rise in the german ca tended to worsen the rea trade balance but had a weak effect on rea real activity our analysis suggests these driving factors are likely to be slowly eroded leading to a very gradual reduction of the german ca surplus an expansion in german government consumption and investment would raise german gdp and reduce the ca surplus but the effects on the surplus would be weak

efficient estimation methods for closed ended contingent valuation surveys closed ended contingent valuation surveys can be very useful in the evaluation of nonmarket resources respondents merely state whether they would accept or reject a hypothetical threshold amount either as payment for giving up access to the resource or as a fee for its use the authors develop a maximum likelihood procedure which exploits the variation in the threshold values to allow direct and separate point estimates of regression like slope coefficients and error standard deviations without truncation bias their illustration uses data from a survey of recreational fisherman to examine factors which influence individuals willingness to pay copyright 1987 by mit press

contingent valuation and social choice the contingent valuation method for estimating the existence value of natural resources is examined for psychophysical robustness statistical reliability and economic sensibility extensions of standard models for willingness to pay and suitable econometric techniques for analyzing these models are developed the analysis is applied to a series of experiments on the value of preserving wilderness areas in the western united states the results call into question the reliability of the cv method for estimating existence values

implementing the efficient allocation of pollution we provide simple mechanisms to implement the efficient allocation of pollution first assuming complete information across firms and then allowing for incomplete information both mechanisms operate by inducing firms to monitor one another using firms reports to determine pollution allotments and transfers the complete information mechanism determines a firm s transfer according to a linear pollution price set by other firms both mechanisms can be modified to be budget balanced in and out of equilibrium the complete information mechanism implements the efficient allocation even when firms are allowed to use mixed strategies under a single crossing condition the same holds for the incomplete information mechanism this abstract was borrowed from another version of this item

recreation demand models with taste differences over people we estimate random parameter logit models of anglers choice of fishing site the models generalize logit by allowing coefficients to vary randomly over anglers rather than being fixed the models do not exhibit the restrictive independence from irrelevant alternatives property of logit and can represent any substitution pattern estimation explicitly accounts for the fact that the variation in coefficients over anglers induces correlation in unobserved utility over trips by the same angler willingness to pay for improved fish stock and the value to anglers of specific sites are calculated from the models and compared with the estimates obtained from a standard logit model

full extraction of the surplus in bayesian and dominant strategy auctions we consider auctions for a single indivisible object in the case where the bidders have information about each other which is not available to the seller we show that the seller can use this information to his own benefit and we completely characterize the environ ments in which a well chosen auction gives him the same expected payoff as that obtainable were he able to sell the object with full information about each bidder s willingness to pay we provide this characterization for auctions in which the bidders have dominant strate gies and for those where the relevant equilibrium concept is bayesian nash in both set ups the existence of these auctions hinges on the possibility of constructing lotteries with the correct properties we consider the situation in which an agent the seller possesses one indivisible unit of a good to which he attaches no value but the good has value to a number of potential buyers and its transfer to one of them would increase social welfare in particular the transfer to the buyer with the highest valuation maximizes social welfare in this paper we completely characterize environments in which the seller can design an auction that will enable him to capture for himself the full increase in social welfare induced by the transfer of the good to the bidder with the highest willingness to pay if the seller had full information about the reservation prices of potential buyers his optimal selling strategy would be very simple he would announce a price equal or very close to the highest reservation value the optimal strategy for the bidder with the highest evaluation would be to accept the offer note that we are treating a situation in which the seller can commit himself to a price as a result of the exchange the utility of the seller increases by the full amount of the increase in social welfare and he has been able to fully extract the surplus in many circumstances however a seller has only imperfect knowledge of the buyers willingnesses to pay in this case he must find some mechanism or auction which will enable him to maximize his benefit from the sale of the object the auction literature starts with this observation and shows how the seller can by an astute choice of auction extract the largest possible fraction of the surplus in general the literature has shown that this proportion is strictly less than one in some circumstances the bidders will have information about each other which is not available to the seller for instance in auctions for petroleum drilling rights bidders know the results of geological tests which they have

the role of question order and respondent experience in contingent valuation studies abstract grand canyon white water boating was used to address issues in contingent valuation of question ordering and respondent experience question ordering effects were not identified for experienced boaters but did occur in some estimates for less experienced boaters an experience effect is further suggested if respondents value their actual white water trips differently than written scenarios of trips no effect was identified for experienced boaters but a significant difference did occur for less experienced boaters significant differences for less experienced boaters suggest that respondent experience may play a role in value formation resulting in survey instrument effects in valuation estimates