booms busts and babies health we study the relationship between the unemployment rate at the time of a baby s conception and parental characteristics parental behaviors and babies health babies conceived in times of high unemployment have a reduced incidence of low and very low birth weight fewer congenital malformations and lower post neonatal mortality these health improvements are attributable both to selection changes in the type of mothers that conceive during recessions and to improvements in health behavior during recessions black mothers tend to be higher socio economic status as measured by education and marital status in times of high unemployment whereas white mothers are less educated

family planning in a life cycle model with income risk several us states have recently restricted the access to abortions we study fertility intentions and how family planning and abortions are used as mechanisms to control fertility among couples facing income risk we formulate and estimate a life cycle consumption saving model with uninsurable income risk and imperfect contraceptive control that matches fertility behavior in the british household panel survey bhps well we use the estimated model to investigate how family planning and abortions are used to control fertility in our model our simulations suggest that income risk affects family planning and that abortion is used to control fertility due to the presence of income risk this indicates that the availability of abortions might play a role as an insurance mechanism

teen motherhood and abortion access it is argued that the net effect of any restriction of abortion access on birth rates is an empirical question this study examines the impact of access to abortion on county teenage birth rates birth rates are expected to decrease by 1 among white adolescents aged 15 19 years for a 25 mile increase in the distance to the nearest abortion provider particularly among in wedlock births data are obtained from 1973 88 national natality local area summary files for counties in the us and four other national sources data did not provide useful information on the empirical relationship between access and birth rate for densely populated urban areas cross sectional findings that had omitted variable bias indicate that an increase of 25 miles in distance to a provider was associated with an additional 1 4 births per 1000 white teenage women or a 3 increase in the average teen birth rate of 45 1000 white teenagers the findings from a county fixed effects model that controlled for omitted variable bias indicate that an increase of 25 miles was associated with a reduction in teen births of 0 5 1000 or about 1 of the mean birth rate both medicaid restrictions and parental consent laws were negative and significant and more negative in poor and more isolated counties the state year effects models did not change findings on distance and medicaid restriction effects the effects of changes in timing of laws suggests that laws followed preexisting trends changes in distance to provider were primarily in the first 2 years following the change out of wedlock births were unaffected by changes in distance to providers the out of wedlock teen birth rate increased with a complete ban on abortions fewer wanted births were associated with small restrictions findings imply that closing of clinics during 1977 88 had an impact on teen birth rates of under one tenth of 1 the 20 increase in teen births was unexplained

risk aversion and arbitrage this paper characterizes conditions under which asset returns and consumption are consistent with risk averse preferences it is shown that risk aversion is equivalent to zero arbitrage on a transformation of the payoff space the implicit state prices which are dual to this no arbitrage condition can be interpreted as prices of pure consumption hedges this zero arbitrage restriction implies the usual restrictions associated with nonsatiation the analysis holds in both complete and incomplete market settings through a number of recent papers in financial economics we have come to understand that the absence of arbitrage opportunities is equivalent to the existence of positive implicit state claim prices in addition given a particular allocation of consumption quantities for different states of the world absence of arbitrage is necessary and sufficient for the consumption plan to be a consumer optimum for some monotonic preference ordering the purpose of this paper is to inquire into the additional restrictions on asset returns imposed by requiring that an allocation be a consumer optimum when preferences are concave monotonic von neumann morgenstern vnm stateindependent and defined over a single good we find that a necessary and sufficient condition is that there is absence of arbitrage not only on the original payoff space but also on a simple transformation of the payoff space this transformation has an intuitively appealing form and can be interpreted as a type of risk adjustment perhaps the classic development of the duality between absence of arbitrage and positive implicit state prices is contained in ross 9 working with a finite number of assets and states ross shows that when positive state prices exist and price returns in a manner consistent with the observed market values of the assets arbitrage is precluded when markets are complete the implicit state prices are uniquely determined and it is easy to check if they are positive more generally there will be many vectors of state prices which value assets in a manner consistent with their observed market prices absence of arbitrage opportunities implies that at least one of these is positive analogues of this result have been shown to hold in more general environments by garman 3 ross 10 harrison and kreps 6 and hansen and richard 5 among others several authors have also noted that zero arbitrage restrictions are necessary and sufficient for an arbitrary positive consumption bundle to be a consumer optimum for some set of monotonic preferences kreps 7 provides perhaps the most general discussion of this point both authors from graduate school of industrial administration carnegie mellon university

social approval values and afdc a re examination of the illegitimacy debate this paper models the fertility decision of individuals who differ in their wage rate and their intensity of preferences for rearing children and whose utility of having a child out of wedlock depends on the level of social approval associated with doing so this social approval in turn is a function of the fraction of individuals in previous generations that chose to have children out of wedlock the model is a straightforward extension of the typical rational choice model that motivates much of the empirical literature a literature that has cast doubt on a strong link between afdc and illegitimacy however the model introduces elements from epidemic models that many have in mind when arguing for such a link as a result the predictions of this extended model are consistent with empirical findings while at the same time linking the rise in illegitimacy solely to government welfare programs specifically a program similar to afdc is introduced into an economy with low illegitimacy rates and a trans

provider availability race and abortion demand variations in the availability of abortion providers may impact the demand for abortions since greater provider availability reduces the travel cost associated with obtaining an abortion this paper applies a fertility control model to estimate the responsiveness of abortion demand to travel cost variations using individual data from all births and abortions of women over age 20 in the state of texas for 1993 the probability that a pregnant woman chooses an abortion appears to be sensitive to availability induced variations in the travel cost of abortion services controlling for the endogeneity of travel distance the results suggest that pregnant women who reside in counties with longer travel distances to the nearest abortion provider have lower probabilities of aborting their pregnancies than women in counties closer to abortion providers simulations show that changes in travel distance will have relatively large impacts on overall abortion rates and furthermore that these effects vary across race in addition these simulations show substantial differences by race in the effects of changes in other explanatory variables

transitions from home to marriage of young americans the paper examines the impact of income on the transitions between home living independently and first marriage of young americans a matching model is outlined similar to that used in theories of job search to explain the probability of marriage and living alone a multiple state multiple transition model which allows for correlated heterogeneity on the first and subsequent transitions is estimated the results show that income has a strong and significant effect the impact of unobserved heterogeneity is examined in detail the impact of the young person s earnings on the transitions is explored through simulation

incentive effects of the u s welfare system a review the author would like to acknowledge support for prior work on this topic from the u s department of health and human services and helpful comments from three anonymous referees rebecca blank howard chernick john fitzgerald irwin garfinkel peter gottschalk edward gramlich david greenberg judith gueron james heckman v joseph hotz robert hutchens michael keane frank levy larry mead michael murray robert plotnick anuradha rangarajan philip robins howard rolston jeffrey smith and daniel weinberg all opinions and errors are those of the author alone

risk return tradeoff in u s stock returns over the business cycle in the empirical finance literature findings on the risk return tradeoff in excess stock market returns are ambiguous in this study i develop a new qualitative response qr generalized autoregressive conditional heteroskedasticity in mean garch m model combining a probit model for a binary business cycle indicator and a regime switching garch m model for excess stock market return with the business cycle indicator defining the regime estimation results show that there is statistically significant variation in the u s excess stock returns over the business cycle however consistent with the conditional intertemporal capital asset pricing model icapm there is a positive risk return relationship between volatility and expected return independent of the state of the economy

alternative paths to parenthood ivf or child adoption this article analyzes the effects of child adoption on the utilization of assisted reproductive technology art in the united states using state level longitudinal data for 1999 2006 we show that art use is responsive to changes in adoption markets after controlling for state specific fixed effects our estimates reveal that a 10 increase in adoptions leads to a 1 3 1 5 decrease in the number of art cycles performed the responsiveness is higher when we consider infant adoptions adoptions by older women and international adoptions while there is no substitutability between art and adoption of related children jel i11 j13 j18

habit persistence and teen sex could increased access to contraception have unintended consequences for teen pregnancies we develop a dynamic discrete choice model of teen sex and pregnancy that incorporates habit persistence habit persistence has two sources here the first is a fixed cost of having sex which relates to a moral or psychological barrier that has been crossed the first time one has sex the second is a transition cost whereby once a particular relationship has progressed to sex it is difficult to move back we estimate significant habit persistence in teen sex implying that the long run effects of contraception policy may be different from their short run counterparts especially if the failure rate of contraception is sufficiently large programs that increase access to contraception are found to decrease teen pregnancies in the short run but increase them in the long run

the paradox of the pill heterogeneous effects of oral contraceptive access the twentieth century saw dramatic increases in nonmarital births concentrated heavily among poor and working class women in this paper we investigate whether the oral contraceptive pill played a causal role in the rise of nonmarital births exploiting exogenous variation in laws governing access to the pill we find that changes in marital access to the pill increased the nonmarital birthrate by between 15 and 18 accounting for about one third of the overall increase in nonmarital births these effects are concentrated almost entirely among women whose fathers did not graduate high school and among minority women we also document that the pill increased spacing between first and second births and lowered the probability that a woman obtained a high school diploma consistent with increases in nonmarital births we find no evidence that postsecondary education levels were influenced by pill access and no evidence that nonmarital births move with male employment patterns our findings add to a growing literature which documents the power of the pill to shape women s lives in broadly heterogenous ways with minority and less well educated women bearing the brunt of the losses a phenomenon we call the paradox of the pill jel j12 j13 i24

market resolution and valuation in incomplete markets the arrow debreu approach to general equilibrium in an economy has been recognized as one of the most general and conceptually elegant frameworks for the study of financial problems under uncertainty 2 9 equally well known is its elusiveness when it comes to ready application to practical problems like capital budgeting or empirical testing see 6 15 18 however some recent research see 1 3 6 12 16 18 and 19 has made a serious attempt to put the state preference theoretic model in an operational setting breeden and litzenberger 6 have developed an interesting approach to derive constructively the prices of elementary arrow debreu securities from the prices of call options on aggregate consumption banz and miller 3 use a similar technique to value capital budgeting projects based on values for state contingent claims computed from prices of call options written on the market portfolio the supershare securities proposed by hakansson 14 16 and related work by garman 13 ross 24 etc have also served to give the so called state contingent approach a practical flavor

a good man is hard to find marriage as an institution this paper presents a model of marriage as an institution that changes the incentives of a mating game between men and women unlike other models of the family decisions to invest in children are not contractible ex ante but must be sub game perfect given that intimacy and pregnancy are sequential marriage and divorce which are publicly observable create costs for exiting a match informal relationships do not providing an institution which makes a match observable marriage improves incentives for men to invest costly unobservable effort in their children

regulation and the optimal size and type of abortion provider between 1973 the year the supreme court ruled in roe v wade that women have the right to decide whether or not to terminate their pregnancies and 1982 the number of abortion providers increased by 81 per cent however between 1982 and 1992 a period of increasing state level abortion regulation the number of abortion providers decreased by 18 per cent we know very little about the factors that influence the willingness and ability of hospitals clinics and physicians to provide abortion services over time based on state data from 1978 to 1992 the results of this paper suggest that large abortion providers are better able to compete and survive in the market also clinics and physicians offices appear to be gaining market share relative to hospitals further this paper includes analysis of the impact of state level medicaid funding regulations on the number size and type of abortion provider these results have important implications for women s access to abortion services and thus have impor

sex preferences marital dissolution and the economic status of women author s bedard kelly deschenes olivier abstract the rise in the divorce rate over the past 40 years is one of the fundamental changes in american society a seemingly ever increasing number of women and children spend some fraction of their life in single female headed households leading many to be concerned about the economic circumstances of these women their and children estimating the cause to effect relationship between marital dissolution and female economic status is complicated because the same factors that increase marital instability may also affect the economic status and labor market behavior of women we propose an instrumental variables solution to this problem based on the sex of the firstborn child this strategy exploits the fact that the sex of the firstborn child is random and the fact that marriages are less likely to survive following the birth of girls as opposed to boys our iv estimates cast doubt on the contention that marital instability causes large declines in woman s economic status once the negative selection into divorce is accounted for we find that women who have experienced marital dissolution have considerably higher levels of personal income and annual wages than women who remain married at the same time we find little evidence of differential poverty rates and equivalized household incomes among ever divorced women and never divorced women we further show that the higher wages of ever divorced women mostly reflect increased labor supply intensity hours and weeks of work of woman who experienced marital dissolution

access to abortion investments in neonatal health and sex selection evidence from nepal the impact of abortion reforms on the human capital of subsequent generations including health has been documented in several developed countries however i evidence relative to the impact on health in early life is not unanimous ii there is no evidence for a developing country where health human capital is low and iii existing econometric studies have been unable to disentangle the effect of abortion reform on individual behavior from that on the composition of mothers in this paper i exploit variation in the timing and location of newly introduced legal abortion centers in nepal to estimate the effect of reducing the psychological and nancial cost of abortion on fertility investments in prenatal care neonatal mortality and sex selection consistent with the prediction that the opening of a legal abortion center nearby reduces the cost of abortion i find that the probability of a live birth conditional on conception decreases by 8 3 percentage points 9 percent of the mean for a given mother similarly the unconditional monthly probability of a live birth decreases by 0 4 percentage points 21 percent of the mean however there is no evidence that improved access to abortion increases observed investments in antenatal care and little evidence that it increases unobserved investments in neonatal health contrary to ndings in lin et al 2008 for taiwan abortion reform in nepal does not appear to have led to sex selective terminations on the contrary there is some evidence that it may have led to a decrease in sex selective abortion which could be due to the substitution of first trimester legal abortions to illegal abortions at a later gestational stage

cohabitation marriage and divorce in a model of match quality the objective of this research is to further our understanding of how and why individuals enter and leave coresidential relationships we develop and estimate an economic model of nonmarital cohabitation marriage and divorce that is consistent with current data on the formation and dissolution of relationships jovanovic s journal of political economy 87 1979 972 90 theoretical matching model is extended to help explain household formation and dissolution behavior implications of the model reveal what factors influence the decision to start a relationship what form this relationship will take and the relative stability of the various types of unions the structural parameters of the model are estimated using longitudinal data from a sample of female high school seniors from the united states new numerical methods are developed to reduce computational costs associated with estimation the empirical results have interesting interpretations given the structural model they show that a significant cause of cohabitation is the need to learn about potential partners and to hedge against future bad shocks the estimated parameters are used to conduct several comparative dynamic experiments for example we show that policy experiments changing the cost of divorce have little effect on relationship choices

an empirical analysis of adoption i introduction adoption is as old as recorded history it was practiced by the ancient egyptians greeks and romans technically adoption is a legal procedure by which a couple or less commonly an individual takes someone else s child into their family and raises it as their own the child may be unrelated to either adoptive parent but is often the child of one member of the couple or related in some other way to the adoptive parents adoption severs all legal ties between the birth parents and the child and replaces them by a legal relationship between the child and the adoptive parents in most cases of adoption the birth parents voluntarily surrender their parental rights so that an adoption can take place it seems highly likely that the u s supreme court will allow further restrictions on the availability of abortion as a consequence considerable attention is certain to be focused on the adoption option and its social implications prior to 1970 fertility behavior was little studied by economists partly because it was thought that the determinants were largely noneconomic during the past two decades however economists using a choice theoretic framework have examined a variety of fertility issues such as marriage becker 1974 procreation and children detray 1973 birth control willis 1973 and abortion leibowitz eisen and chow 1986 surprisingly no economic research exists on the issue of adoption despite the fact that it represents a natural extension of the traditional theory of consumer choice most adoption research focuses on sociological issues such as infertility or adoption procedures this paper empirically estimates the supply of adoptions using the decision making economic framework of completed fertility developed by becker 1960 and extended by michael 1973 i believe their model s determinants of desired fertility and family size will also be significant in explaining a household s decision to give up a child for adoption section ii outlines the adoption model and relates it to the economic theory of desired fertility and family size the third and fourth sections discuss the empirical estimates of the adoption model the fifth section examines the impact of various state regulations on the adoption decision and the last section discusses public and social implications of the empirical results ii the adoption model michael argues that households decisions concerning desired family size and the timing of childbearing can be explained in terms of a household production function michael s model is based on a comparison of the benefits and costs from an additional child over time his theory of completed fertility purports to be over a household s full reproductive age span but it is in actuality a period by period analysis households are myopic in that although they consider the future costs and benefits of a child an independent decision is made in each period regarding whether to have a child a household s optimal family size may be for example two children but if when the first child is conceived the household perceives the timing of the birth as undesirable then at that point in time the net benefit from the additional child is negative the consequence is that the child is unwanted and the household will take steps to reduce the discrepancy between the desired and actual stock of children one possible solution is an adoption once a child is born a household has two choices keep the child or put it up for adoption michael s framework implies that the likelihood that a household will place a child for adoption is positively related to the negative discrepancy between the household s desired and actual stock of children at that time the factors affecting a household s desired family size income time values relative productivities and revealed tastes are reflected in the discrepancy between the desired and actual stock of children

who buys and who sells options the role of options in an economy with background risk abstract in this paper we derive an equilibrium in which some investors buy call put options on the market portfolio while others sell them since investors are assumed to have similar risk averse preferences the demand for these contracts is not explained by differences in the shape of utility functions rather it is the degree to which agents face other non hedgeable background risks that determines their risk taking behavior in the model we show that investors with low or no background risk have a concave sharing rule i e they sell options on the market portfolio whereas investors with high background risk have a convex sharing rule and buy these options journal of economic literature classification numbers d52 d81 g11 g13

spanning and completeness with options the role of ordinary options infacilitating the completion of securities markets is examined in the context of a model of contingent claims sufficiently general to accommodate the continuous distributions of asset pricing theory and option pricing theory in this context it is shown that call options written on a single security approximately span all contingent claims written on this security and that call options written on portfolios of call options on individual primitive securities approximately span all contingent claims that can be written on these primitive securities in the case of simple options explicit formulas are given for the approximating options and porfolios of options these results are applied to the pricing of contingent claims by arbitrage and to irrelevance propositions in corporate finance

the price of virtue this article offers new evidence on the determinants of u s unwed birth rates from 1981 to 1990 we show that illegitimacy rates are positively and significantly correlated with payments under the aid to families with dependent children program over a period in which real afdc payments declined we attribute this result to a decline in the social sanctions for illegitimacy because social sanctions declined so did the cost of deviance as well as the price for which unwed women sold their virtue

can beer taxes affect teen pregnancy evidence based on teen abortion rates and birth rates economists have investigated the effects of increased alcohol taxes on various alcohol related phenomena like traffic fatalities but to my knowledge this study is the first to investigate the effects of beer taxes on teen pregnancy outcomes namely abortion and birth rates the study employs statelevel data for 15 19 year old women for the years 1985 1988 1992 and 1996 the smallness of the panel imposes some constraints on the statistical methods used results indicate that higher beer taxes have statistically significant negative effects on teen abortion rates though the magnitudes of the effects are quite small effects on birthrates are statistically insignificant this suggests that increased beer taxes may help prevent some unwanted pregnancies that would typically be terminated via abortions rather than culminating in live births however the small magnitudes of the effects strongly caution against relying on increased beer taxes to noticeably reduce teen pregnancy rates

the effect of family planning programs on the fertility of welfare recipients evidence from medicaid claims this paper explores the effectiveness of family planning fp services subsidized by the medicaid program in lowering the fertility of female welfare recipients previous studies used single equation estimates and produced conflicting and sometimes confounding results thus this study employed a bivariate probit model to estimate the effect of contraceptive acceptance on the individuals probability of giving birth without the bias that may result from single equation estimates a unique data set created from maryland medicaid claims records was also used results suggest that medicaid fp programs are much more effective at lowering fertility than indicated by previous studies using single equation estimates

still waiting for mister right asymmetric information abortion laws and the timing of marriage previous studies have suggested that more liberal abortion laws should lead to a decrease in marriage rates among young women as shotgun weddings are no longer necessary empirical evidence from the united states lends support to that hypothesis this article presents an alternative theory of abortion access and marriage based on the cost of search which suggests that more liberal abortion laws may actually promote young marriage an empirical examination of marriage data from eastern europe shows that countries that liberalized their abortion laws saw an increase in marriage rates among nonteenage women

children as income producing assets the case of teen illegitimacy and government transfers this paper develops a classical model of the teen fertility decision in the presence of public income transfers the theoretical model predicts that welfare payments will encourage fertility holding constant other economic opportunities and that better economic opportunities will discourage fertility considering the possible simultaneity of illegitimacy rates and benefit levels due to the collective choice process the authors confirm the theoretical models predictions with state level data from 1980 through 1990 the authors find that including fixed effects in the regression to control for unobserved differences between states does not sufficiently control for endogeneity after controlling for endogeneity real welfare benefits are strongly and robustly related to teen illegitimacy the point estimates of the elasticity with respect to changes in the illegitimacy rate are around 1 3 for white teens and 2 1 for black teens real wages for women with a high school education or less are negatively related to teen illegitimacy for white teens with an elasticity of around 0 4 finally male wages appear to have little effect on the illegitimacy rate for white teens but appear negatively correlated with the illegitimacy rate for black teens in some model specifications authors

does the welfare state destroy the family evidence from oecd member countries we study the effect of the size of the welfare state on family outcomes in oecd member countries exploiting exogenous variation in public social spending due to varying degrees of political fractionalization i e the number of relevant parties involved in the legislative process we show that an expansion in the welfare state increases the fertility marriage and divorce rates with a quantitatively stronger effect on the marriage rate we conclude that the welfare state supports family formation nevertheless we also find that the welfare state decouples marriage and fertility and therefore alters the organization of the family authors abstract

abortion legalization and child living circumstances who is the marginal child weexaminethe impact ofincreased abortion availabilityon the averageliving standards of children through a selection effect would the marginal child whowas not born have grown up in different circumstances than the average child we use variation in the timing of abortion legalization across states to answer this question cohorts born after legalized abortion experienced a signiecant reduction in a number of adverse outcomes we end that the marginal child would have been 40 60 percent more likely to live in a single parent family to live in poverty to receive welfare and to die as an infant access to abortion is one of the most contentious public policy issues facing the united states today the period since the legalization of abortion under the roe v wade decision of 1973 has been marked by incessant debate over the appropriate government enancing and legal status of abortions meanwhile pregnancy resolution through abortion is a very common outcome in the united states roughly 25 percent of all pregnancies are aborted ventura et al 1995 as a result major changes in abortion access could have substantial effects on the birthrate indeed levine staiger kane and zimmerman end that the legalization of abortion in the early 1970s led to an 8 percent reduction in the birthrate 1

efficient funds for meager asset spaces abstract for finite state space models of securities markets there exists a portfolio of traded securities on which conventional call or put options suffice to complete securities markets 28 moreover these efficient funds are generic 2 18 the objective of this paper is to present a class of larger models of securities markets for which existence and genericity of efficient funds obtains conditions abstracted from the finite state space case serve to define a meager asset space it is shown that for meager asset spaces satisfying a separability condition efficient funds exist and are generic in a category theoretic sense

noncooperative bargaining models of marriage in this paper we discuss some simple noncooperative models of distribution within marriage in which the equilibria are not necessarily pareto optimal in which history and culture can affect which equilibrium is realized and in which distribution may depend on whether resources are controlled by the husband or by the wife recent moves away from single decision maker models of the family have permitted economists to address distribution within marriage and cooperative bargaining models have played the central role in these moves the next step is to permit strategic interaction between family members by modeling distribution within marriage as a noncooperative game noncooperative game theory allows great flexibility in specifying the rules of the game and unlike cooperative game theory imposes few a priori restrictions on the nature of equilibrium outcomes in particular noncooperative models neither assume nor imply that all equilibria are pareto optimal

how the other half lived marriage and emancipation in the age of the pill abstract the contraceptive pill was fda approved in 1960 however it would be another decade before young unmarried women had full access in the meantime marriage constituted a way to the pill the later 1960s early 1970s also saw a convergence on 18 as the minimum age of marriage many states lowering it from 21 exploiting these law changes we find that a lowered minimum age precipitated marriage delayed marital fertility and improved women s educational and occupational outcomes marriage easing credit constraints combined with the contraceptive properties of the pill form the hypothesized pathway

marriage and divorce changes and their driving forces the family is not a static institution in recent decades marriage rates have fallen divorce rates have risen and the defining characteristics of marriage have changed the economic approach to the family seeks to explain these trends by reference to models that can also explain how and why families form gary becker s 1981 treatise on the family proposed a theory based on production complementarities in which husband and wife specialize in the market and domestic spheres respectively production complementarities also arise in the production and rearing of one s own children however production complementarities at least as initially described are decreasingly central to modern family life increased longevity and declining fertility mean that most of one s adult life is spent without one s own children in the household also the rise in marital formation at older ages including remarriage means that many families form with no intention of producing children moreover increases in female labor force participation suggest that household specialization has either declined or at least taken on a different meaning these changes have come about as what is produced in the home has been dramatically altered both by the emergence of labor saving technology in the home and by the development of service industries that allow much of what was once provided by specialized homemakers to be purchased in the market the availabil

who marries whom and why this paper proposes and estimates a static transferable utility model of the marriage market the model generates a nonparametric marriage matching function with spillover effects it rationalizes the standard interpretation of marriage rate regressions and points out its limitations the model was used to estimate u s marital behavior in 1971 72 and 1981 82 the marriage matching function estimates show that the gains to marriage for young adults fell substantially over the decade unlike contradictory marriage rate regression results the marriage matching function estimates showed that the legalization of abortion had a significant quantitative impact on the fall in the gains to marriage for young men and women

state abortion rates the impact of policies providers politics demographics and economic environment abstract this paper uses data on abortion rates by state from 1974 1988 to estimate two stage least squares models with fixed state and year effects restrictions on medicaid funding for abortion are correlated with lower abortion rates in state and higher rates among nearby states a maximal estimate suggests that 19 25 of the abortions among low income women that are publicly funded do not take place after funding is eliminated parental notification laws for teen abortions do not significantly affect aggregate abortion rates a larger number of abortion providers in a state increases the abortion rate primarily through inducing cross state travel

an analysis of out of wedlock childbearing in the united states this paper relates the erosion of the custom of shotgun marriage to the legalization of abortion and the increased availability of contraception to unmarried women in the united states the decline in shotgun marriage accounts for a significant fraction of the increase in out of wedlock first births several models illustrate the analogy between women who do not adopt either birth control or abortion and the hand loom weavers both victims of changing technology mechanisms causing female immiseration are modeled and historically described this technology shock hypothesis is an alternative to welfare and job shortage theories of the feminization of poverty excerpt

a path dependent approach to security valuation with application to interest rate contingent claims abstract the last two decades have witnessed a tremendous growth in the volume of assets and liabilities whose cash flows depend in a variety of ways on the path of interest rates some of these including floating rate notes and swap agreements contractually base cash flows on current and past interest rates and contain caps floors and other more complex features others including mortgages many corporate bonds and time deposits are fixed rate instruments that contain embedded options such as those to prepay call or withdrawal the irregular exercise of these options causes cash flows to vary as time proceeds and interest rates rise or fall this paper develops a state contingent claims technique for valuing such securities it is derived from the option based model of breeden and litzenberger 1978 using the transition matrix approach of banz and miller 1978 particular attention is paid to valuing so called path dependent securities whose contemporaneous cash flows depend on the historical path of interest rates as well as their current level a detailed example is provided in which an adjustable rate mortgage is valued under a variety of economic and security specific assumptions

why have divorce rates fallen the role of women s age at marriage american divorce rates rose from the 1950s to the 1970s peaked around 1980 and have fallen ever since the mean age at marriage also substantially increased after 1970 i explore the extent to which the rise in age at marriage can explain the decrease in divorce rates for cohorts marrying after 1980 using data from the survey of income and program participation 1979 national longitudinal survey of youth and national survey of family growth three different empirical approaches suggest that the increase in women s age at marriage is the main proximate cause of the fall in divorce rates

why is it so difficult to uncover the risk return tradeoff in stock returns abstract the low power of the standard wald test in a garch in mean model with an unnecessary intercept is shown to explain the apparent absence of a risk return tradeoff in stocks the importance of this finding is illustrated with monthly u s data

what determines family structure i introduction the most prevalent type of family structure in which children in the united states are raised today is the traditional one in which both biological parents are present in the home and married but in the past 30 40 years it has become increasingly common for children to experience alternative family structures such as living with the mother with no father present the mother and a stepfather and cohabiting parents children who grow up in a family with married biological parents have better education employment marriage childbearing and psychological outcomes on average than their counterparts who spend substantial parts of childhood living in alternative family structures 1 these differences are generally quite large and dwarf the effects of income and maternal employment the evidence suggests that at least part of the association between family structure and child outcomes is causal there is much still to be learned about the consequences of growing up in alternative family structures but there is a consensus that family structure matters for child development in contrast there is much less known about the determinants of family structure the proximate determinants of family structure are well studied demographic behaviors union formation and dissolution transition from cohabitation to marriage and fertility both in and outside of unions but the implications of adult demographic behaviors for the family structure experiences of children depend crucially on interactions among these behaviors for example the impact on a child of being born out of wedlock is likely to depend on whether the mother and biological father subsequently marry or cohabit and if so how soon after the birth of the child the impact on a child of the dissolution of a union may depend on whether the man in the union was the child s biological father or a stepfather and on the duration of the union economic theories of family formation and dissolution suggest a number of observable factors that affect the demographic behaviors that determine family structure 2 these include the wage rates available to men and women the tax and transfer incentives to cohabit marry and bear children the legal environment governing divorce and child support provided by absent parents and the state of the marriage market many studies have examined the effects of these factors on the family structure experiences of children but most have taken a narrow approach for example a typical study examines the impact of changes over time in one or two determinants of family structure without considering the implications of simultaneous changes in other factors most studies examine only one or two of the key demographic behaviors that determine the family structure experienced by children for example one study might focus only on entry to cohabitation and marriage whereas another study examines childbearing while single and a third study analyzes marital dissolution in this article we propose a new approach to analyze the determinants of the family structure experiences of children our approach has four distinguishing features first we jointly model union formation union dissolution and childbearing decisions previous analyses have integrated some of these behaviors in a single model but none has integrated the full range of behaviors needed for a thorough analysis of family structure a major feature of change in recent years has been de linking of marriage and childbearing decisions hence it is crucial to recognize as emphasized by ellwood and jencks 2004 that marriage and childbearing are in fact distinct decisions and that treating single parenthood as one decision rather than the consequence of related but distinct union and childbearing decisions misses key elements of changes in behavior furthermore bumpass and lu 2000 point out that a substantial part of the increase in single parenthood in the last three decades can be accounted for by a rise in the presence of children with cohabiting parents but child outcomes are worse in cohabitation than marriage other things equal

short term market risks implied by weekly options we study short maturity weekly s p 500 index options which provide a direct way to analyze volatility and jump risks unlike longer dated options they are largely insensitive to the risk of intertemporal shifts in the economic environment adopting a novel seminonparametric approach we uncover variation in the negative jump tail risk which is not spanned by market volatility and helps predict future equity returns as such our approach allows for easy identification of periods of heightened concerns about negative tail events that are not always signaled by the level of market volatility and elude standard asset pricing models

spanning with index options current literature stresses that efficient funds do not exist when asset returns are contin uously distributed this paper shows that the existence of efficient funds can be restored if security returns are generated by a linear factor model

long term impacts of childhood medicaid expansions on outcomes in adulthood we use administrative data from the internal revenue service to examine long term impacts of childhood medicaid eligibility expansions on outcomes in adulthood at each age from 19 to 28 greater medicaid eligibility increases college enrolment and decreases fertility especially through age 21 starting at age 23 females have higher contemporaneous wage income although male increases are imprecise together both genders have lower mortality these adults collect less from the earned income tax credit and pay more in taxes cumulatively from ages 19 to 28 at a 3 discount rate the federal government recoups 58 cents of each dollar of its investment in childhood medicaid

an economic analysis of the demand for abortions research in estimating the demand for abortions is conducted by using an economic model and examining socioeconomic factors some suggest that a households fertility control decision is decided by a comparison of the costs and benefits of an additional child over a period of time therefore abortion is a choice related to the interaction of preference cost and income a womans marital status is another factor in the abortion decision an unmarried women may having a greater demand for abortion since the demands on her are greater another factor is a womans employment status an employed woman more likely having a higher abortion religious affiliation may be another determinant in lower demand for abortion since most religions oppose abortion however in surveys of catholic women 74 believed that a woman less than 3 months pregnant should make her own choice on abortion educational status was also thought to effect abortion demand but results showed no significance if the laws were changed abortion were illegal and the price increased 50 the abortion rate would drop by 40 5 the prohibiting of government funding for abortions would cause a 17 5 decrease future trends in abortion are likely to increase however due to the declining marriage rates and increased divorce rate other factors that will effect these trends include sexual behavior patterns contraceptive availability and the perceived risks involved in birth control

children and their parents a review of fertility and causality childbearing decisions are not made in isolation they are taken in concert with decisions regarding work marriage health investments and stocks as well as many other observable and non observable considerations drawing causal inferences regarding the effect of additional children on family outcomes is complicated by these endogenous factors this paper lays out the issues involved in estimating the effect of additional child births on family outcomes and the assumptions underlying the range of estimators and methodologies proposed in the economic literature the common pitfalls of these estimators are discussed as well as their potential to bias our interpretation of the effect additional births have on children and parents both in the existing literature and in future work in the face of changing patterns of childbearing and child rearing

u s abortion policy and fertility as measured by the total fertility rate tfr fertility in the united states fell sharply beginning in the early 1960 s dropping to below the replacement level in 1972 and to well below the replacement level in the late 1970 s since then the tfr has hovered below replacement level also in the early 1970 s several states followed by the u s supreme court in its 1973 roe v wade decision legalized abortion this paper explores whether there is a connection between changes in abortion policy and u s fertility since the initial legislation legalizing abortion government abortion policies continue to change with government policies in general becoming less sympathetic to abortion this shift is most notable in states decisions to end federal funding for abortions through medicaid in the late 1970 s and most recently in some of the provisions of the federal 1996 welfare reform legislation specifically the personal responsibility and work opportunities act of 1996 prowra included illegitimacy bonuses for the five states that are most successful in reducing the number of out of wedlock births while decreasing abortion rates committee on ways and means 1996 proposals to further restrict abortion as well as proposals to liberalize abortion continue to receive active consideration despite large numbers of abortions more than one for every three live births the effect of abortion policy on the number of children born is not clear in the parallel debate about the oral contraceptive some claimed that the new contraceptive technology caused the decline in fertility in the mid 1960 s others claimed that the oral contraceptive simply made the decline less costly for couples in the

accounting for the gender gap in college attainment i introduction one striking phenomenon in the u s labor market is the reversal of the gender gap in college attainment in 1980 57 of young men aged 25 34 compared with 46 of young women had some college education by age 34 by 1996 however female college attainment had reached 64 5 percentage points higher than that of the males in the same cohort in tact females overtook males in college attainment in 1987 and have led ever since a large body of empirical research emphasizes the role of the earnings premium as a key explanatory variable for the determination of education outcomes see e g becket 1967 mincer 1974 willis and rosen 1979 in addition an extensive literature shows that family background is an important determinant of the schooling decision see among others cameron and heckman 1998 2001 eckstein and wolpin 1999 ge 2008 kane 1994 recently several papers have argued empirically and theoretically that expected marriage is important in determining the schooling decision e g chiappori iyigun and weiss 2006 ge 2008 iyigun and walsh 2007 on the basis of this literature we construct a life cycle model that includes potential costs and benefits from the labor market and marriage market which determine individual college decisions in our model individuals with differing learning abilities first decide whether or not to enter college then they might get married and have children parents are altruistic and value their children s learning ability which increases with the parents education forward looking individuals take into account the impact of their own schooling on their children s learning ability other factors that affect an individual s decision on whether to pursue higher education include the expected direct labor market returns to college over one s lifetime the expected marriage market returns to college and the financial and effort costs of attending college these costs and benefits can differ by gender we calculate from panel study of income dynamics psid and current population survey cps parents education distributions the life cycle profiles of single marriage and divorce probabilities by education and the lifecycle profiles of earnings by education and marital status as exogenous inputs of the model we observe that the number of college educated parents increases over time in the marriage market a substantial increase of single probabilities and an increase of divorce probabilities has occurred for both genders regardless of college attainment status lifetime earnings by cohort are decreasing slowly for males of all marital statuses especially for married males lifetime earnings for married and divorced females are increasing gradually whereas those for single females are decreasing slightly to formally endogenize those changes is beyond the scope of our paper we instead focus on the mechanism in which under perfect foresight these changes affect education decisions we estimate the parameters of the model by matching data on college attainment by gender from the psid we present evidence on how well the model fits the data we then use the parameter estimates to simulate counterfactual experiments which break down the sources of changes in college attainment into the effects of changes in relative earnings changes in parental education and changes in the marriage market what accounts for the increase in college attainment over the past few decades we find that the increasing gap in earnings between college and high school graduates has important effects on the increase in college attainment for both genders when earnings are fixed at 1946 cohort levels attainment rates in 1996 drop by 15 5 and 14 2 percentage points for males and females respectively we also emphasize the importance of intergenerational persistence in schooling on the increase in college attainment for both genders

equilibrium open interest abstract this paper analyses what determines an individual investor s risk sharing demand for options and aggregating across investors what the equilibrium demand for options we find that agents trade options to achieve their desired skewness specifically we find that portfolio holdings boil down to a three fund separation theorem that includes a so called skewness portfolio that agents like to attain our analysis indicates also however that the common risk sharing setup used for option demand and pricing is incompatible with a stylized fact about open interest across strikes

canadian contributions to family economics canadian scholars have made substantial contributions to the relatively new field of family economics these include new models of how men and women match in marriage markets and of how decisions are made in multi person households several were early contributors to the literature on married women s labour supply and labour supply in a family context and helped to develop empirical methods in this area a particular focus has been on the impacts of policy relevant parameters such childcare costs on family labour supply and child well being new work on child development the impact of early life conditions and the processes of intergenerational transmission also highlight the importance of family context in determining economic well being

birth control and female empowerment an equilibrium analysis we analyze from a theoretical perspective the impact of innovations in birth control technology on intrahousehold allocation of resources we consider a model of frictionless matching on the marriage market in which men as well as women differ in their preferences for children moreover men unlike women must marry to enjoy fatherhood we show that more efficient birth control technologies generally increase the power hence the welfare of all women including those who do not use them this empowerment effect requires that the new technology be available to single women an innovation reserved to married women may result in a disempowerment effect

efficient funds in a financial market with options a new irrelevance proposition under the same assumptions that ross used to assert the existence of an efficient fund on which a spanning set of options can be written we prove that almost any portfolio is an efficient fund from a constructive point of view a randomly chosen vector of portfolio weights yields an efficient fund when the ross assumptions are relaxed a limited notion of efficiency maximal efficiency is the best attainable the maximally efficient funds are also everywhere dense in the portfolio space some implications are discussed and illustrative examples given the theory of consumer and firm behavior in economies with a complete set of contingent claims is rather well understood these complete market structures1 bring about competitive equilibria where consumers maximize utility firms maximize profits and prices adjust to match demand and supply as shown in debreu 7 all competitive equilibria are pareto optimal and any pareto optimum can be sustained as a competitive equilibrium it is commonly recognized however that complete markets have not come into

regulation imperfect competition and the u s abortion market the u s abortion market has grown increasingly concentrated recently while many states tightened abortion laws using data on abortion providers i estimate an equilibrium model of demand price competition entry and exit to capture the effect of regulation on industry dynamics estimates show regulations played an important role in determining the abortion market structure and evolution counterfactual simulations reveal increases in demand aimed regulation were the most important observed factor in explaining recent abortion declines simulating utah s regulatory regime nationally shows tightening abortion restrictions can increase abortions in equilibrium mainly through tilting the competitive landscape toward low price providers

tying the double knot the role of assets in marriage commitment what explains the growing gap in marriage rates between socioeconomic groups we present a robust stylized fact not previously documented marriage rates are higher for individuals with more assets we argue this may be driven by marriage and cohabitation becoming increasingly similar in a number of ways except for the way assets become marital property to be divided upon divorce in marriage while they remain individual property in the case of cohabitation we propose that ownership of assets may provide insurance to the partner making individually costly but jointly optimal investments in children thus raising the value of marriage

the effect of medicaid abortion funding restrictions on abortions pregnancies and births this paper considers whether state medicaid abortion funding restrictions affect the likelihood of getting pregnant having an abortion and bearing a child we exploit a natural experiment afforded by supreme court decisions and employ more traditional multivariate models with alternative fixed effect specifications an analysis of 12 years of state level data indicate that restrictions are associated with a reduction in abortions and either no change or a reduction in births implying fewer pregnancies subsequent analysis of the national longitudinal survey of youth nlsy is consistent with these findings and show the response is concentrated among the low income population

a complete analysis of full pareto efficiency in financial markets for arbitrary preferences this paper provides a complete analysis of the necessary and sufficient conditions for financial markets to achieve fully pareto efficient allocation of aggregate wealth through trade in economies with arbitrary preferences we show that full pareto efficiency obtains only if the market structure of contingent claims spans the information partition of a minimal aggregate wealth statistic and a halmos savage sufficient statistic for the beliefs of the traders all the known allocation efficiency results in the literature due to arrow hakansson john ross and others are unified by this result a security is a certificate that entitles the holder to a stream of cash flows

spanning and completeness in markets with contingent claims abstract we characterize financial markets that are complete or that contain portfolios which span all measurable functions of a particular asset payoffs either finite and infinite dimensional these results are then employed to describe the extent to which options trading is sufficient to complete markets to investigate the existence of efficient funds and to establish the extent of market completeness required to ensure the unanimity and irrelevance results of modern corporation finance

put call parity and market frictions abstract we extend the fundamental theorem of finance and the pricing rule representation theorem to the case in which market frictions are taken into account but the put call parity is still assumed to hold in turn we obtain a representation of the pricing rule as a discounted expectation with respect to a nonadditive risk neutral probability

the american family and family economics abstract gary becker s path breaking treatise on the family 1981 subjected individuals decisions about sex marriage childbearing and childrearing to rational choice analysis the american family has changed radically in recent decades we survey these changes as well as the ongoing effort to understand partnering parenting and care of the elderly as results of maximizing choices made by individuals first we describe the recent changes in the american family the separation of sex marriage and childbearing fewer children and smaller households converging work and education patterns for men and women class divergence in partnering and parenting strategies and the replacement of family functions and home production by government programs and market transactions second we examine recent work in family economics that attempts to explain these changes third we point out some challenging areas for further analysis and highlight issues of commitment in two primary family relationships those b

the supply of infants relinquished for adoption did access to abortion make a difference motivated by a theory of desired fertility i use three years of aggregate state level data to examine the impact of abortion access on the supply of infants relinquished for adoption i show evidence that abortion access affected the supply of infants relinquished during the 1980s in two different ways first the availability of abortion providers has the expected effect of reducing the supply of infants relinquished particularly relative to the demand for abortion second abortion law has an unexpected negative effect this suggests that as abortion laws become more restrictive the total number of unwanted births may decrease jel j13

saying i don t the effect of the affordable care act young adult provision on marriage this paper investigates the effect of the affordable care act young adult provision on the propensity to marry the young adult provision expanded options for obtaining insurance coverage outside of marriage young adults affected by the provision might have less incentive to marry since one avenue for obtaining health insurance coverage is through marriage this paper examines this question by applying difference in differences type methods using the 2008 2013 american community survey results suggest that the provision is associated with decreases in the likelihood of marrying cohabitation and spousal health insurance coverage and an increase in the probability of divorce

persistence of occupational segregation the role of the intergenerational transmission of preferences this article provides an explanation of the evolution and persistence of the women s segregation in jobs with less on the job training opportunities within the framework of an overlapping generations model with intergenerational transmission of preferences job priority and family priority preferences are considered firms policy and the distribution of women s preferences are endogenously and simultaneously determined in the long run the results show though the gender gap in training will diminish it will also persist over time this is because both types of women s preferences coexist at the steady state due to the socialisation effort of parents to preserve their own cultural values

income inequality and early nonmarital childbearing using individual level data from the united states we empirically investigate the role of lower tail income inequality in determining rates of early nonmarital childbearing among low socioeconomic status ses women we present robust evidence that young low ses women are more likely to have a nonmarital birth when they live in places with larger lower tail income inequality all else held constant we calculate that differences in the level of inequality are able to explain a sizeable share of the geographic variation in teen fertility rates we propose a model of adolescent decision making that facilitates the interpretation of our results

estimating the factors determining the demand for induced abortions among married women in taiwan this paper purports to estimate the characteristics of women who had experiences of abortion in 1991 based on an economic model of fertility the study makes use of a national survey on the knowledge of attitude towards and practice of family planning and reproductive health among married women in taiwan the results show that older women with higher family income and who live in urban areas were more likely to have the pregnancy terminated in addition the decision to have an abortion was negatively correlated with prior pregnancy loss but positively associated with the number of previous live births on the other hand the availability of abortion services as measured by the number of legal abortion providers at city and county levels had a negative effect on the demand for abortions the local female unemployment rate was found to be positively correlated with the woman s decision to have an abortion

investigating the intertemporal risk return relation in international stock markets with the component garch model abstract daily data and component garch cgarch models strongly support a positive risk return relation in contrast to previous international results long run volatility appears to be important in determining the conditional equity premium but the evidence might be spurious

the economics of fatherhood the growth of nonmarital fertility together with greatly increased divorce rates and an increased proportion of children living in femaleheaded households has provoked considerable alarm about the demise of the traditional family and concern about potentially harmful effects on the well being of women and children in this paper i briefly summarize recent attempts by myself and others to develop a coherent theoretical framework to integrate economic theories of fertility and marriage in order to better understand why the same men who play the breadwinner role within marriage may fail to support their children following a divorce or who despite the gains to marriage may prefer to father children out of wedlock rather than within marriage i argue that such behaviors of men can be understood within a framework that takes into account the selfinterests of both men and women as they interact within a given sexual or marital match and as they interact in a broader market for sexual and marriage partners at the level of a given match the theory provides hypotheses about the determinants of voluntary child support by fathers who are divorced from or have never married the mother it also suggests reasons why voluntary child support is likely to be inadequate and consequently provides some insight about the role of laws and administrative procedures designed to establish paternity determine the size of childsupport awards and enforce collection of awards at the level of the market under certain circumstances theory produces results similar to those emphasized by william wilson and katherine neckerman s 1987 theory of outof wedlock childbearing among the underclass

the role of economic incentives in teenage nonmarital childbearing choices abstract in this paper we explore whether behaviors of youths that are likely to result in a teen nonmarital birth event are influenced by their expectations of the net economic benefits or costs associated with the occurrence of such a birth we posit and find that an increase in the perceived costs associated with the occurrence of a nonmarital birth would lead to a reduction in these risky behaviors and to a lower probability of a nonmarital birth event we represent these economic incentives by the income expectations of young women conditional on either giving birth as an unmarried teen or forgoing childbearing while unmarried and an adolescent we also measure the effects of an extensive list of other factors including the characteristics of the girl s family and its choices the social and economic environment in which she lives including policy related factors such as expenditures by states on family planning programs and the generosity of aid to families with dependent children and her own prior choices

voting with the crowd do single issues drive partisanship we examine whether survey data supports the anecdotal evidence which suggests that group association impacts the individual s stated beliefs specifically we examine whether a rise in the relative importance of a single issue i e national security blurs the traditional importance of socio economic variables in determining an electorate s political party association further we examine whether such blurring occurs across the responses to questions outside the scope of this single issue we find that in the aftermath of the terrorist attacks on 11 september 2001 the relative importance of national security rose in the us electorate and reduced the relative importance of socio economic variables in determining the electorate s political association for both security and nonsecurity issues

why have women become left wing the political gender gap and the decline in marriage the last three decades have witnessed the rise of a pohtical gender gap in the united states wherein more women than men favor the democratic party we trace this development to the decline in marriage which we posit has made men richer and women poorer data for the united states support this argument first there is a strong positive correlation between state divorce prevalence and the political gender gap higher divorce prevalence reduces support for the democrats among men but not women second longitudinal data show that following marriage divorce women are less more likely to support the democratic party

the impact of legalized abortion on crime we offer evidence that legalized abortion has contributed significantly to recent crime reductions crime began to fall roughly eighteen years after abortion legalization the five states that allowed abortion in 1970 experienced declines earlier than the rest of the nation which legalized in 1973 with roe v wade states with high abortion rates in the 1970s and 1980s experienced greater crime reductions in the 1990s in high abortion states only arrests of those born after abortion legalization fall relative to low abortion states legalized abortion appears to account for as much as 50 percent of the recent drop in crime

the impact of state abortion restrictions on minors demand for abortions this study uses a weighted least squares model and a fixed effects model to estimate the impact of parental consent laws and laws governing medicaid funding of abortions on the adolescents demand for abortion in the united states during 1978 90 the focus is on adolescent pregnancy because 12 of total legal abortions in 1987 were to adolescents aged under 18 years the rate of abortion and types of abortion law range widely between states data are obtained from the us center for disease control on reported abortions from the naral foundation on the dates of actual enforcement restrictions and from the alan guttmacher institute on abortion providers the empirical model is based on a model developed by grossman and joyce proxy measures are used to represent abortion sentiment fixed effects models indicated that there was a decline of 13 17 in adolescents demand for abortion in states with enforced parental involvement laws compared to states without enforced laws the results implied a 9 15 decline in adolescents demand for abortion in states that restricted medicaid funding of abortion compared to states that did not there was a positive association between abortion demand and income and between abortion demand and the availability of abortion providers the inclusion of the abortion sentiment proxies did not change the signs and magnitudes of the impact very much in the fixed effects models it is posited that the negative impacts of abortion restrictions on adolescent abortion demand cannot be attributed to unobserved heterogeneity four methods of modeling are used to account for the potential role of unobserved heterogeneity