bounded price variation and rational expectations in endogenous switching model of the u s corn market a model that includes bounded price variation and rational expectations by producers is estimated for the u s corn market the resulting model specification is highly nonlinear though since the probability of market equilibrium must be determined endogenously unlike previous research the cross equation restrictions implied by the rational expectations hypothesis are incorporated in the bounded prices model by using fair and taylor s 1983 procedure for obtaining maximum likelihood estimates of nonlinear rational expectations models the resulting model is compared against a standard equilibrium model with naive expectations the results show the bounded prices model is a superior specification copyright 1989 by mit press

dynamic corn supply functions a model with explicit optimization both static and dynamic models have been used to estimate aggregate supply elasticities for annual crops the early studies relied on static singleequation models in a few variables assumed static price expectations e g kohls and paarlberg and produced very small estimates of own price supply elasticities e g 0 07 for corn nerlove 1956 1958a and nerlove and addison showed that agricultural supply models incorporating adaptive price expectations and or dynamic resource adjustment produced larger estimates of supply elasticities for corn and other agricultural commodities additionally they showed that supply elasticities obtained from static models need not be bounded by the short run and long run supply elasticities of

agricultural price instability a survey of competing explanations and remedies there are two explanations for agricultural price dynamics one follows cobweb logic and models fluctuations driven by expectation errors but emphasises that these expectations create complex dynamics and possibly chaos the other stems from the rational expectations tradition of dynamics driven by real shocks the empirical evidence tends to support the latter but is not conclusive the rational expectations model generates an optimal dynamic path from which no improvement can be expected from public intervention however if we take account of all the potential market failures in agricultural markets and especially in developing countries this conclusion might require some qualifications although an appropriate policy design for stability has still to be achieved this paper surveys the positive and normative literature on agricultural prices highlighting empirical evidence and identifying remaining unresolved issues

evaluating the impacts of real time pricing on the usage of wind generation one of the impediments to large scale use of wind generation within power systems is its nondispatchability and variable and uncertain real time availability operating constraints on conventional generators such as minimum generation points forbidden zones and ramping limits as well as system constraints such as power flow limits and ancillary service requirements may force a system operator to curtail wind generation in order to ensure feasibility furthermore the pattern of wind availability and electricity demand may not allow wind generation to be fully utilized in all hours one solution to these issues which could reduce these inflexibilities is the use of real time pricing rtp tariffs which can both smooth out the diurnal load pattern in order to reduce the impact of binding unit operating and system constraints on wind utilization and allow demand to increase in response to the availability of costless wind generation we use and analyze a detailed unit commitment model of the texas power system with different estimates of demand elasticities to demonstrate the potential increases in wind generation from implementing rtp

acreage decisions under risk the case of corn and soybeans an acreage supply response model is developed under expected utility maximization the resulting framework is used to specify and estimate a system of risk responsive acreage equations for corn and soybeans in the united states particular attention is given to the truncation effects of government price supports on the distribution of corn and soybean prices also a wealth variable is included in the acreage equations the empirical results indicate that risk and wealth variables play an important role in cornsoybean acreage decisions the analysis also shows that cross commodity risk reduction is important in acreage allocation decisions

looking for evidence of speculative stockholding in commodity markets abstract the theory of commodity price with speculative storage predicts that prices are a two regime process depending on whether or not inventories are held the price process is nonlinear in that it is nondifferentiable at some p which separates the data into a history independent regime and an autoregressive process this paper looks for evidence of nonlinearity in the price data and tests the theory in the context of threshold autoregressive models under the assumption that shocks to harvest are i i d while we find evidence for regime specific behavior we also find the degree of persistence in the stockout regime to be much stronger than that predicted by theory

estimation of dynamic nonlinear rational expectations models of primary commodity markets with stochastic dynamic programming and disequilibrium maximum likelihood methods are combined to estimate a dynamic nonlinear rational expectations model of a market for a storable primary commodity the estimation model captures the inherently nonlinear structure of private stockholding dynamics the disequilibrium effects of government buffer stock intervention and the impact of price expectations and risk on private supply and stockholding decisions copyright 1993 by mit press

the strategic bequest motive although recent research suggests that intergenerational transfers play an important role in aggregate capital accumulation our understanding of bequest motives remains incomplete we develop a simple model of strategic bequests in which a testator influences the decisions of his beneficiaries by holding wealth in bequeathable forms and by conditioning the division of bequests on the beneficiaries actions the model generates falsifiable empirical predictions that are inconsistent with other theories of intergenerational transfers we present econometric and other evidence that strongly suggests that bequests are often used as compensation for services rendered by beneficiaries

inter vivos transfers and intergenerational exchange the surge of interest in intergenerational transfers in the past decade has sparked a debate over the motivation for them are transfers given out of altruism or part of an exchange while each motive is probably at work to some extent we know little about whether one motive predominates the question is relevant for issues concerning public income redistribution and inequality in the family but despite its importance empirical evidence about motives is scarce because of limited data we investigate a new data set the national survey of families and households which remedies many of the shortcomings of other data sets containing private transfer information we find that empirical patterns for inter vivos transfers i e transfers between living persons are more consistent with exchange than altruism

bivariate garch estimation of the optimal commodity futures hedge six different commodities are examined using daily data over two futures contract periods cash and futures prices for all six commodities are found to be well described as martingales with near integrated garch innovations bivariate garch models of cash and futures prices are estimated for the same six commodities the optimal hedge ratio ohr is then calculated as a ratio of the conditional covariance between cash and futures to the conditional variance of futures the estimated ohrs reveal that the standard assumption of a time invariant ohr is inappropriate for each commodity the estimated ohr path appears non stationary which has important implications for hedging strategies

bequest motives and fertility decisions abstract we compare altruistic and strategic bequest motives and examine which one induces the higher demand for children although parents with strategic bequests have the stronger demand for filial attention they choose to have fewer children than those with altruistic bequests

a reexamination of the strategic bequest motive this paper investigates the strength of the empirical evidence of the strategic bequest hypothesis proposed by bernheim shleifer and summers 1985 at issue is whether bequests are primarily motivated by a desire to influnce the behavior of potential beneficiaries alternatively bequests may be motivated by altruism or risk aversion in the presence of incomplete annuity and health insurnace markets e g tomes 1981 hurd 1989

the effects of social security on population and output growth in this paper we have considered two unfunded social security programs under the conventional system benefits are related to aggregate fertility under the hypothetical fertility related system benefits are directly linked to individual fertility the effects on fertility and per capita growth rates of the two social security systems are examined in the context of endogenous growth the relative merits of the two systems for developing and developed countries are considered the authors conclude that the conventional social security system existing in many developed nations may be desirable to developing countries in reducing population and promoting economic growth on the other hand the hypothetical fertility related system may be useful to developed countries as far as increasing fertility is concerned

specification of the joy of giving insights from altruism this paper analyzes the joy of giving bequest motive in which the utility obtained from leaving a bequest depends only on the size of the bequest it exploits the fact that this formulation can be interpreted as a reduced form of an altruistic bequest motive to derive a relation between the value of the altruism parameter and the value of the joy of giving parameter using previous discussions of an a priori range of plausible values for the altruism parameter we then derive plausible restrictions on the joy of giving parameter we demonstrate that this parameter may well be orders of magnitude larger than assumed in the existing literature this abstract was borrowed from another version of this item

operative gift and bequest motives the ricardian equivalence theorem which is the proposition that changes in the timing of lump sum taxes have no effect on assumption or capital accumulation depends on the exist of operative altruistic motives for intergenerational transfers these transfers can be bequests from parents to children or gifts from children to parents in order for the ricardian equivalence theorem to hold one of these transfer motives must be operative in the sense that the level of the transfer is not determined by a corner solution resulting from a binding non negativity constraint this paper derives conditions that determine whether the bequest motive will be operative the gift motive will be operative or neither motive will be operative in a model in which consumers are altruistic toward their parents and their children this abstract was borrowed from another version of this item

new evidence on altruism a study of tiaa cref retirees this paper investigates the role in household wealth accumulation of saving for bequests it employs data from a 1988 survey of tiaa cref annuitants designed to measure pension and other net worth as well as lifetime earnings about half of the households in the data plan to leave estates and the authors find that their behavior conforms with theoretical altruistic models for the same families the amount of wealth that the authors attribute to estate building is large nevertheless altruism towards one s children does not seem to be the major explanation of saving in the overall sample copyright 1996 by american economic association

the effects of commodity price stabilization programs in this paper the authors analyze the effects of commodity programs in which the government attempts to support and stabilize price through open market purchases and sales specifically they as sess the effects of such programs on the u s soybean market using a rational expectations model that allows for private storage expected price responsive production and arbitrary support and release price s a salient feature of the model is that private storage and product ion behavior adjusts to changes in government policy stochastic simu lations of the market model demonstrate that price stabilization prog rams can reduce long run market price and destabilize producer revenu e copyright 1988 by american economic association

on the pitfalls of multi year rollover hedges the case of hedge to arrive contracts it is shown that it is theoretically infeasible for multi year rollover hedge to arrive contracts and for rollover hedges in general to succeed at locking in high current prices for crops to be harvested one or more years into the future the study utilizes 107 years of data to present strong empirical evidence that the corn market behaves remarkably similarly to what price theory predicts results also confirm that short historical time series are unreliable for predicting rare events hence empirical studies of risk management contracts capitalizing on unusual occurrences should use samples sufficiently large to contain a meaningful number of relevant observations copyright 2001 oxford university press

optimal transmission switching sensitivity analysis and extensions in this paper we continue to analyze optimal dispatch of generation and transmission topology to meet load as a mixed integer program mip with binary variables representing the state of the transmission element line or transformer previous research showed a 25 savings by dispatching the ieee 118 bus test case this paper is an extension of that work it presents how changing the topology affects nodal prices load payment generation revenues cost and rents congestion rents and flowgate prices results indicate that changing the topology to cut costs typically results in lower load payments and higher generation rents for this network computational issues are also discussed

how much of commodity price behavior can a rational expectations storage model explain a rational expectations competitive storage model was applied to the u s corn market to assess the aptness of this framework in explaining monthly price behavior in an actual commodity market relative to previous models extensive realism was added to the model in terms of how production activities and storage costs are specified by modeling convenience yield backwardation in prices between crop years did not depend on the unrealistic assumption of zero ending stocks our model generated cash prices that were distributed with positive skewness and kurtosis and mean and variance that increased over the storage season comparable to the persistence and the occasional spikes observed in commodity prices futures prices were generated as conditional expectations of cash prices at contract maturity and the variances of futures prices exhibited realistic time to maturity and seasonal patterns model realizations of cash and futures prices over many years were used to demonstrate the wide variety of price behaviors that could be observed in an efficient market with a similar market structure implying that economic and policy implications drawn from short historical samples of prices could be misleading

bubbles in food commodity markets four decades of evidence abstract we use daily prices from individual futures contracts to test whether speculative bubbles exist in 12 agricultural markets and to identify whether patterns of bubble behavior exist over time the samples begin as far back as 1970 and run through 2011 the findings demonstrate that all 12 agricultural markets experienced multiple periods of price explosiveness however bubble episodes represent a very small portion between 1 5 and 2 of price behavior during the 42 year period in addition most bubbles are short lived with 80 90 lasting fewer than 10 days though receiving far less attention negative bubbles contribute significantly to price behavior accounting for more than one third of explosive episodes markets over react during both positive and negative explosive episodes leading to a correction as they return to a random walk this adjustment back to fundamental values is most pronounced with positive bubbles particularly in the earlier part of the sample while the magnitudes of the corrections are generally small there were a few instances of significant increases in prices and large over reactions most notably in the softs e g cocoa 1973 coffee 1994 cotton 2010 we also find that explosive periods did not become more common or last longer in the second half of the sample period and that the most recent bubble episodes may not have been as severe as in mid 1970s

bequest behavior and the effect of heirs earnings testing the altruistic model of bequests that parents transfer resources to children because of altruistic concern is a reasonable a priori assumption however economic theories of altruistic transfers have produced many counterintuitive conclusions and consequently much debate when applied to bequests these theories predict that inheritances will compensate for earnings differences between siblings as well as between parents and children this paper tests these implications using a new data set centered on federal estate tax returns little support can be found for an altruistic theory of bequests this finding has implications for macroeconomic policy government transfer programs and inequality copyright 1996 by american economic association

social security and private saving new time series evidence in an important article in the journal of political economy martin feldstein 1974 estimated that the introduction of the social security system had reduced personal saving by 50 percent with serious consequences for capital formation and output his conclusion was based on a consumer expenditure function estimated with u s time series data and incorporating a social security wealth variable of his construction this paper presents new evidence that casts considerable doubt on feldstein s conclusion first the social security wealth variable used by feldstein was seriously flawed as a result of a computer programming error simply correcting this error substantially changes the estimated effect of social security on saving second the statistical evidence depends upon assumptions which are embedded in the construction of the social security wealth variable assumptions that are not demonstrably preferable and are in some cases inferior to alternative assumptions these assumptions relate first to how individuals form their expectations about the social security benefits they expect to receive and the social security taxes they expect to pay and second to estimates of the number of workers dependent wives and surviving

modeling expectations of bounded prices an application to the market for corn the presence of farm programs should directly affect the expectations of producers this paper analyzes the formation of price expectations when price supports constitute an effective lower bound on the distribution of the expectations we first investigate what the expected price would be if the usual rational expectations formula is used this leads to a relationship that is not estimable we suggest two alternatives one based on a tobit approximation and the other based on a perfect prediction of when the support is going to be effective using a simplified model of the u s corn market the methodology is demonstrated and compared to an alternative method of using futures prices as the expectation of harvest price the analysis of supply response for the major u s field crops is made difficult due to government intervention in these markets this intervention has been characterized by the use of price supports acreage diversion storage incentives etc during the last thirty years many studies have analyzed producer behavior in the presence of governmental involvement such studies have typically been concerned with modeling the effect of supports and diversions in an ex post sense rather than with how producers used the knowledge of farm programs to form their expectations if producers are rational economic agents their expectations of harvest prices should be conditioned both by free market forces and the type and degree of governmental intervention in the market of course farm programs have varied in nature and extent during the past thirty years and it is doubtful that any structural model could capture their complexities in this paper we attempt to introduce rational expectations in a simplified model of the u s corn market in essence we focus on the formation of price expectations when price supports constitute an effective lower bound on the distribution of the expectations we proceed by developing a theoretical model that connects the rational expectations model with a model of bounded price variation it is shown that one representation that may characterize the corn market is a triangular structural system with endogenous switching a full information maximum likelihood estimator is proposed for the system next an empirical model is specified and estimated the model is evaluated in comparison to an augmented model that contains a futures price so that some inferences may be made concerning the rational expectations model s success in summarizing relevant market information expectations under bounded prices consider a market that may be represented by a simple supply and demand system q a pt a2w el supply function pt b qt b2xt e2t demand function 1 where p and q represent market price and quantity w and x represent supply and demand shifters and p represents the rational expectation of product price at the time production decisions are made note that this system has a familiar recursive structure when the expected price variable is specified in terms of one or more lagged prices when the restricted reduced form of the structural system is solved for in terms of the expected price and this expression is used to replace pj wallis 1980 then models similar to those of goodwin and sheifrin 1982 and shonkwiler and emerson 1982

what explains price volatility changes in commodity markets answers from the world palm oil market abstract what are the sources of commodity price volatility changes based on observation of the palm oil market 1818 1999 our hypothesis is that the superimposition of short distance operators located near the export supply whose expectation horizon is limited to a few weeks and long distance operators further from the export supply whose expectation horizon exceeds six months to one year is responsible for volatility changes and market instability because of the superimposition of expectations horizons volatility grows along with the development of short distance trade we support this hypothesis using a trader behavior model derived from day and huang j econ behavior org 14 1990 299 and day complex economic dynamics vol i mit press cambridge ma our simulation results challenge the argument that trade liberalization and market enlargement necessarily reduce commodity prices volatility

the inefficiency of interest rate subsidies in commodity price stabilization interest rate subsidies have been used to stimulate commodity stockholding with the intention of stabilizing prices however reductions in price variability can be achieved at less government cost using a direct storage subsidy and it is possible that an interest rate subsidy will increase price variability even though the interest subsidy increases mean stocks held these results are demonstrated using a stochastic dynamic programming model of optimal private storage with parameter values relevant to agricultural commodity markets and with particular reference to the u s soybean market

generalized optimal hedge ratio estimation a generalized approach to estimating optimal hedge ratios on futures markets is developed the generalized approach is not difficult to apply and provides a framework for evaluating the appropriateness of conventional simple regression approaches to optimal hedge ratio estimation in an application to storage hedging of corn soybeans and wheat it is found that simple regression using price levels or returns leads to errors in optimal hedge ratio estimation but that simple regression using price changes provides reasonably accurate estimates

autoregressive conditional heteroscedasticity in commodity spot prices muth s 1961 rational expectations model of commodity markets implies that inventory carryover creates arch processes in prices the model also indicates that the expected price variance is an explanatory variable in price regressions hypotheses were tested on price data of twenty commodities using a variation of engle et al 1987 arch m technique an arch process was found in storable and not in non storable commodity data as expected however changes in expected price variance have no significant impact on price copyright 2001 john wiley sons ltd

the behavior of bid ask spreads in the electronically traded corn futures market this is the first paper to analyze liquidity costs in agricultural futures markets based on the observed bid ask spread bas faced by market participants the results reveal a highly liquid corn market that mostly offers order execution at minimum cost the bas responds negatively to volume and positively to price volatility but also affects volume traded and price volatility while statistically significant these responses on a cents bushel or a percentage basis are generally small liquidity costs are also virtually impervious to short term changes in demand for spreading and trend following trader activity as well as differences from day of the week changes in market activity much larger cents bushel and percentage changes in bas occur during commodity index trader roll periods and on usda report release days the roll period findings indicate a sunshine trading effect while announcement effects identify the importance of unexpected information and adverse selection on order execution costs overall our research demonstrates that the transition to electronic trading in the corn futures market has led to low and stable liquidity costs despite the market turbulence in 2008 2009

estimating a nonlinear rational expectations commodity price model with unobservable state variables this paper is concerned with the estimation of a model in which a possibly serially correlated stochastic process the harvest of an agricultural commodity generates a competitive price in a market comprising both final consumers and risk neutral speculators who can store the commodity at a cost in the anticipation of profit because storage cannot be negative the relationship between prices and harvests is inherently nonlinear and is an unpromising candidate for a linear quadratic model or for linearization more generally instead we calculate numerically a policy function in which price is a function of two unobservable state variables the harvest and current availability and we use the result to fit the price data

extent and possible causes of intrayear agricultural commodity price volatility wheat corn rice soybeans and cotton experienced higher volatility in the second half of the 2000s for the sample at hand the unit root tests only validate a new period of high volatility for wheat and cotton if in the next couple of years however corn rice and soybeans maintain their higher volatility a new period of high volatility may also be validated statistically regarding the factors driving the intrayear volatility gmm estimates show that commodity market fundamentals i e the stock to use ratio and to a lesser extent the degree of internationalization are the most systematically statistically significant coefficients among commodities over time consecutive low stock to use ratios and a thin international market provoke typically high volatility speculative activity and liquidity in the agricultural derivative market have a stabilizing effect on the spot price if any finally common macro factors significantly impact volatility especially the volatility of petrol and of exchange rates their dispersion importance over the sample is quite sizeable however it is difficult to establish a link between on the one hand loose monetary policy business cycle and inflation and on the other hand commodity price volatility as the sign of the estimated coefficient changes depending on the commodity and the estimated elasticities are quite low

price dynamics in biological production processes exposed to environmental shocks this paper demonstrates a mechanism by which environmental shocks in biological production processes can lead to extreme price movements and thus be a contributing factor to short term food price volatility in biological production processes environmental shocks can lead to a stock out when the harvest transitions to a new stock year class with a different marginal value the result in the market is a temporary price spike or bubble bounded by the marginal value of the new stock we highlight this phenomenon in a cohort or year class biological production setting each year class in the model is a finite non renewable capital stock and capital theory is used to solve for the stochastic dynamic competitive equilibrium the model is parameterized to be representative of the norwegian salmon aquaculture industry results suggest that the model can replicate much of the observed patterns in price harvest and capital stock dynamics including the infrequent occurrence of extremely high prices in the market

tractable transmission topology control using sensitivity analysis the standard economic generation dispatch ed minimizes generation costs subject to transmission constraints where the status of each line i e open or closed is fixed recent research shows that by optimally dispatching the network topology along with generation resources significant congestion costs may be avoided optimal topology control i e appropriate changes of transmission line status for real sized power networks requires the solution of a computationally intractable mixed integer linear program however it appears that much of the cost savings may be attained by changing the status of just a few lines this paper proposes tractable transmission topology control policies which employ sensitivity information readily available from the ed to select candidate lines to change status while maintaining system connectivity implementation on the ieee 118 bus test system found that our best performing policy captured an average of 96 of the potential cost savings moreover the limited computational effort required suggests that these policies could be employed in real system operations

the value of public information in commodity futures markets abstract the informational value of u s department of agriculture usda corn and soybean production forecasts is investigated for the period 1971 1992 three tests of informational content are applied overall the results suggest usda corn and soybean forecasts provide valuable information to participants in commodity futures markets this value does appear to have declined especially since the mid 1980s

the role of intergenerational transfers in aggregate capital accumulation this paper uses historical u s data to directly estimate the contribution of intergenerational transfers to aggregate capital accumulation the evidence presented indicates that intergenerational transfers account for the vast majority of aggregate u s capital formation only a negligible fraction of actual capital accumulation can be traced to life cycle or hump savings a major difference between this study and previous investigations of this issue is the use of more accurate longitudinal age earnings and age consumption profiles these profiles are simply too flat to generate substantial life cycle savings this paper suggests the importance of and need for substantially greater research and data collection on intergenerational transfers life cycle models of savings that emphasize savings for retirement as the dominant form of capital accumulation should give way to models that illuminate the determinants of intergenerational transfers

u s farm policy and the volatility of commodity prices and farm revenues a dynamic three commodity rational expectations storage model is used to compare the impact of the federal agricultural improvement and reform fair act of 1996 with a free market policy and with pre fair policies results suggest that fair did not lead to significant increases in long run price volatility or revenue volatility the main impact of pre fair relative to the free market regime was to substitute government storage for private storage in a way that did little to support prices or to stabilize farm incomes results also indicate that u s grain market volatility in 1995 2000 was due to fundamental market forces and not to fair copyright 2002 oxford university press

are harvest forecasts news usda announcements and futures market reactions futures market price data for maize and soyabeans are used to examine reactions to us department of agriculture harvest forecasts these forecasts are widely known and reasonably accurate so failure to find significant reaction would indicate that the usda did not contribute additional news relative to information already possessed by traders various t tests f tests and nonparametric chi square tests indicate rejection of the null hypothesis of no significant difference between means of absolute values or variances of changes in closing prices on days following a usda announcement and other days thus the data indicate that significant information is contained in the forecasts

altruism the samaritan s dilemma and government transfer policy this paper shows that altruism provides an efficiency rationale for public provision of insurance to the poor the framework is one in which there are rich altruists and risk averse poor who face some possibility of loss the government represents the rich and makes transfers on their behalf with unconditional transfers the poor may forgo insurance and rely on private charity to bail them out in the event of loss this reliance on private charity has adverse efficiency effects these may be avoided if the government makes in kind transfers of insurance copyright 1995 by american economic association

what causes commodity price backwardation a recently proposed explanation for futures price backwardation is examined an equilibrium model with spatial heterogeneity leads to the interpretation of backwardations as mismeasurement by the analyst however the model predicts that backwardations are more affected by the location of stocks than by their aggregate level empirical examination of the united states corn market fails to support this result

impact on corn prices from reduced biofuel mandates press reports indicate that the environmental protection agency may significantly reduce ethanol mandates to levels that can easily be met to gain insight into what this decision implies about the price of corn we use a new model of the corn and rin markets to project corn and ethanol prices and quantities through the 2019 marketing year under two ethanol mandate scenarios the first scenario is the status quo where mandates that can be met with corn ethanol increase to 14 4 billion gallons in 2014 and 15 billion gallons in 2015 and thereafter mandates at this level can only be met using e85 so also included in this scenario is 5 000 new locations where e85 can be purchased the second scenario holds mandates at 13 billion gallons a level that can be met with e10 the price of corn is higher by between 5 and 6 percent about 25 cents per bushel in the higher mandate scenario rin prices are close to zero most of the time in the lower mandate scenario and average between 50 and 60 cents in the higher mandate scenario though the corn price difference is economically meaningful to corn farmers and livestock feeders it is small compared to the price swings that the market has experienced since 2006 this modest change in corn prices from alternative mandate levels suggests that the level of mandate should be determined more by consideration of broad policy objectives rather than the impact on the price of corn of key importance to the advanced biofuel industry is whether policy will support the expansion of biofuels consumption by creating incentives to invest in flex cars and fueling stations that will facilitate expanded consumption of low carbon ethanol consideration of the costs and benefits of creating these incentives as part of a national energy policy is of greater long run importance than the impact of mandates on the price of corn

a theory of commodity price fluctuations this paper studies the price fluctuations of storable commodities that are traded in open markets and are subject to random shocks to demand or more particularly to supply it relaxes the common assumption that the shocks are identically and independently distributed in favor of temporally dependent and periodic disturbances the existence of a unique stationary rational expectations equilibrium is demonstrated for each of the models analyzed and testable implications of the models are derived an illustrative empirical investigation is then undertaken for the model with periodic disturbances using monthly time series observations for seven commodities over the period 1960 93

motives for private income transfers private income transfers are becoming increasingly recognized as a key aspect of the u s economy the majority of private income transfers occur inter vivos i e between living persons but very little is known about this type of transfer behavior this paper tests alternative hypotheses concerning motivation for inter vivos transfers two motives are considered altruism and exchange evidence presented here casts doubt on the altruistic model of transfer behavior observed patterns for inter vivos transfers are more consistent with exchange related motives this finding has important implications for the effects of public transfer programs on the distribution of economic well being

why does on farm storage fail to mitigate price volatility we analyze the role of farm stock management on price volatility under liquidity constraints and heterogeneous price expectations in commodity markets speculative behaviors by stockholders tend to reduce price volatility but this is not the case in certain agricultural markets where speculation by farmers regarding decisions to sell or store grain are subject to liquidity constraints and heterogeneous price expectations like stockholders most farmers sell grain if they expect a price drop in the near future but unlike stockholders they are not necessarily able to purchase grain if they expect a price increase in the next period heterogeneous price expectations can also lead to suboptimal storage decisions further increasing price volatility for these reasons the storage management behavior of farmers often fails to mitigate price drops in the way that speculation by stockholders does we merge historical data on maize prices and household storage collected in burkina faso in order to build a dynamic panel over the 2005 2012 period we show that carry over from one season to the next is associated with unexpected price drops during the preceding lean season and that carry over is associated with more frequent unexpected price drops following the subsequent post harvest season this article is protected by copyright all rights reserved

estimating supply response in the presence of farm programs previous empirical research on crop supply response has given insufficient attention to the fundamentally different nature of supply response under farm programs versus competitive markets a simple theoretical model is presented which highlights the program participation option in the farmer s acreage allocation decision the model also provides the basis for different expected supply elasticities under free market and farm program regimes for corn and soybeans econometric supply estimation for corn belt states for 1948 80 using a temporally disaggregated approach confirms a greater supply elasticity for corn and a lower supply elasticity for soybeans under acreage restricting feed grain programs

parental altruism and inter vivos transfers theory and evidence this paper uses psid data on the extended family to test whether inter vivos transfers from parents to children are motivated by altruism specifically the paper tests whether an increase by one dollar in the income of parents actively making transfers to a child coupled with a one dollar reduction in that child s income results in the parents increasing their transfer to the child by one dollar this restriction on parental and child transfer income derivatives is derived for the standard altruism model augmented to include uncertainty and liquidity constraints these additional elements pin down the timing of inter vivos transfers the method used to estimate income transfer derivatives takes into account unobserved heterogeneity across families in the degree of altruism the findings strongly reject the altruism hypothesis redistributing one dollar from a recipient child to donor parents leads to less than a 13 cent increase in the parents transfer to the child far less than the one dollar increas

competitive storage and commodity price dynamics by buying cheap and selling dear risk neutral commodity speculators can smooth commodity prices and induce serial dependence in price even when none would exist under a simple process of supply and demand commodity prices are variable and strongly positively correlated from one year to the next the variability is often explained by supply factors and the autocorrelation by the activities of speculators we show that this explanation is not consistent with the evidence speculation can substantially increase autocorrelation for prices that are weakly autocorrelated in its absence but not to the high levels that are observed in the data

economic behavior under uncertainty a joint analysis of risk preferences and technology a method is developed to estimate jointly risk preferences and technology under general conditions the approach is illustrated in an application to the analysis of u s corn soybean acreage decisions over time the results provide useful information on the nature of farmers risk preferences and on the influence of price risk and production risk on acreage allocation and farmers welfare copyright 1996 by mit press

precautionary saving and accidental bequests this paper presents a simple general equilibrium model of precautionary saving and accidental bequests this model is used to analyze the implications of individual lifetime uncertainty for aggregate consumption and capital accumulation a precautionary demand for saving arises because an individual consumer does not know in advance the date at which he will die and he wants to avoid low levels of consumption in the event that he lives longer than expected an implication of this precautionary saving is that when death does occur the consumer is generally holding some wealth which is then passed on to his heirs in the form of an accidental bequest even if all consumers have the same ex ante mortality probabilities there will be some intracohort variation in the date of death consequently there will be a nondegenerate distribution of bequests left by consumers in a cohort this nondegenerate distribution of bequests left by one generation induces variation in the distributions of wealth consumption and bequests of subsequent generations the importance of bequests in aggregate saving has been established by laurence kotlikoff and lawrence summers 1981 who reported that 80 percent of u s household wealth is inherited wealth one interpretation of this finding is that the simple life cycle model without bequest motives is an inadequate description of saving behavior in the united states but the model i present demonstrates that accidental bequests by selfish consumers can account for a potentially sizeable fraction of aggregate wealth although some part of bequests especially by the wealthy undoubtedly results from an explicit bequest motive accidental bequests also play a role in the intergenerational transfer of wealth as well as in the intragenerational variation in wealth in order to focus on the role of accidental bequests i purposely exclude a bequest motive from the specification of the utility function the effects of lifetime uncertainty on individual consumption behavior were first examined formally in a seminal paper by menachem yaari 1965 yaari s model provided the basic framework for virtually all subsequent work on uncertain lifetimes including well known papers by nils hakansson 1969 stanley fischer 1973 robert barro and james friedman 1977 david levhari and leonard mirman 1977 and kotlikoff and avia spivak 1981 however all of these papers focused on the consumption decision of an individual and ignored the effect of accidental bequests on the behavior of the recipients of these accidental bequests 2 as will be shown at various points in this paper changes in the economic environment can have effects on aggregate behavior which differ sharply from the effects on individual behavior because of the endogenous adjustment of bequests the effects of department of economics harvard university cambridge ma 02138 this paper is a revised version of bequests and social security with uncertain lifetimes nber working paper no 1372 june 1984 i thank olivier blanchard john burbidge christopher cavanagh robert clower stanley fischer benjamin friedman elhanan helpman mervyn king nobuhiro kiyotaki laurence kotlikoff robert mcdonald james pesando julio rotemberg lawrence summers lars svensson mark watson and jeffrey wolcowitz for valuable conversations and correspondence i also thank the participants in seminars at boston university columbia university cornell university federal reserve board harvard university university of iowa mit university of minnesota university of montreal national bureau of economic research north carolina state university the wharton school and yale university and two anonymous referees for their helpful comments i also thank the national science foundation for financial support 1 in the presence of perfect annuity and life insurance markets there may or may not be bequests depending on the presence or absence of a bequest motive but there would be no accidental bequests 2 kotlikoff and spivak focus on the role of the family in providing an incomplete annuities market but stop short of a full scale overlapping generations model in which the distribution of bequests is determined endogenously

bequest motives social security and economic growth junxi zhang this article conducts a systematic analysis of four bequest motives in a simple model of endogenous growth it analyzes how bequest motives affect fertility savings growth and the effects of pay as you go social security it is found that altruistic and exchange motives give equivalent outcomes if the discount factors are set the same the outcome under the joy of giving motive may involve a higher bequest ratio higher saving and better growth rates than that under altruism if bequests are accidental the equilibrium values will depend on the probability of survival moreover the results provide testable implications on bequest motives jel d1 d9 h55 j1 i introduction although the importance of bequests in aggregate savings has been established by kotlikoff and summers 1981 who reported that 80 of u s household wealth is inherited wealth what bequest motives lead to inheritance remains an unsolved problem yet it is well known that bequest motives have important implications for the behavior of financial markets the macroeconomic impacts of fiscal policies and the intergenerational transmission of inequality in the distribution of wealth at least four hypotheses for the existence of bequests have been discussed in the literature 1 bequests may arise from intergenerational altruism that is parents obtain utility from their heirs utility as well as from their own consumption barro 1974 2 the prospect of bequests is used by parents to induce children to behave as desired by parents bernheim et al 1985 3 bequests may arise from the joy of giving that is parents leave bequests simply because they obtain utility directly from the bequest yaari 1964 1 and 4 bequests may be the unintentional by product of precautionary savings and a stochastic date of death in the absence of an annuity market abel 1985 following barro 1974 and becker 1974 the altruistic bequest motive has been used most frequently however the enormous empirical work using micro data has not led to conclusive evidence on the one hand bernheim et al 1985 cox 1987 and cox and rank 1992 show that bequests are more consistent with exchange than altruism altonji et al 1992 1997 also show that altruism is decisively rejected moreover wilhelm 1996 finds little support for an altruistic theory of bequests on the other hand a recent reexamination of the exchange motive by perozek 1998 shows that the finding of bernheim et al is not robust laitner and juster 1996 find some evidence of altruistic bequests therefore a definite conclusion on bequest motives seems far from over indeed though altruism has not been supported by most of those empirical studies it remains a plausible hypothesis and continues to be used frequently see e g coate 1995 and davies and zhang 1995 abel 1985 argues theoretically that although the simple life cycle model without bequest motives is an inadequate description of the savi ng behavior in the united states as found in kotlikoff and summers 1981 accidental bequests by selfish consumers can account for a sizable fraction of aggregate wealth however little formal empirical work has been done to test whether bequests are accidental or arise from joy of giving given the lack of consensus on bequest motives it is interesting to conduct a systematic theoretical analysis of different bequest motives in a particular context becker et al 1990 and caballe 1995 assume altruism in their models of economic growth wiedmer s 1996 analysis of social security and growth does not consider bequests except ihori 1994 there seems to be no analysis of other bequest motives in the context of economic growth the purpose of this article is to analyze how different bequest motives affect fertility savings and economic growth the article will also examine how the effects of pay as you go social security depend on bequest motives

stochastic unit commitment with topology control recourse for power systems with large scale renewable integration in this paper we model topology control through transmission switching as a recourse action in the day ahead operation of power systems with large scale renewable generation resources we prove that transmission switching could only reduce the linear objective value of direct current optimal power flow when congestion exists however we also show through a simple example that unit commitment cost could be reduced by transmission switching even in the absence of congestion to solve the stochastic unit commitment with topology control within reasonable computational time we proposed a heuristic that first decomposes a practical system into zones and then solves the problem for each zone in parallel the benefit of topology control recourse is demonstrated on a network representing the central european system we compare the costs of the network with different loading and renewable generation conditions the cost reduction of the test system can reach 3 34 with heavy load and large scale renewable generation while in a single zone the cost reduction can be above 7

love thy children abstract this paper proves that barro s 1974 debt neutrality proposition whose relevance hinges in an economy with bequest motives on bequests being operative in the economy without public debt is not applicable to a wide class of overlapping generation economies those with a weak bequest motive in particular it is shown that the bequest motive is always too weak and public debt therefore non neutral when non physical assets have a well defined function reducing oversavings in the corresponding economy without bequest motive i e when the non altruistic economy is dynamically inefficient

gender bias investments in children and bequests the impacts of pure sex preference and differential earnings opportunities by gender on investments in children are modelled with altruism if bequest constraints do not bind human investments are privately efficient with the higher earning gender receiving more education education does not depend on parental wealth the gender differential in bequests is ambiguous however even in this case when bequest constraints bind education may depend on wealth and it is also possible for the gender with better earnings opportunities to get less education the model is tested with data from philippine villages where bequest constraints are generally nonbinding the schooling differential slightly favors daughters estimated bequest behavior however reflects pure sex preference in terms of our model copyright 1995 by economics department of the university of pennsylvania and the osaka university institute of social and economic research association

intergenerational transfers and demographic transition abstract this paper presents an analysis of demographic transition based on the endogenous evolution of intergenerational transfers along an economy s endogenous path of development two period lived agents belonging to overlapping generations choose optimally their desired levels of consumption and fertility together with their desired sizes of transfers to both parents and children parents are more efficient than children in producing output but some parental time must be devoted to child rearing at low levels of development fertility is high and the flow of net intergenerational transfers is from the young to the old at high levels of development fertility is low and the flow of net transfers is from the old to the young these results accord strongly with empirical observations and the analysis may be seen as formalising for the first time a long standing and well respected hypothesis in the demographic transition literature

is the extended family altruistically linked direct tests using micro data this paper uses panel study of income dynamics data on parents and their adult children to test the standard altruism model this model predicts that within the extended family the distribution of consumption is independent of the distribution of resources the authors findings strongly reject this prediction copyright 1992 by american economic association