Social security in a general equilibrium model with endogenous government behavior

In this paper attention is focused on the economic and political effects of an aging population. For that purpose, a general equilibrium model is used that allows for an endogenous analysis of decisionmaking on government policies. We concentrate here on the effects of an aging population on expenditures and levels of social security benefits, the provision of public goods and services, the private output and intergenerational conflicts. Special attention will be paid to the effects of changes in the retirement age and in capital endowments. Furthermore, the effects of issues related to aging, as changes in the political influence structure and the motive of other-directedness by others, are investigated.The authors are grateful to the participants of the ISPE conference. They wish to thank in particular the discussants Jean Frijns, Pierre Pestieau and Harry van Dalen for their helpful comments.     

Aggregation pattern of individuals and the outcomes of competition within and between species: Differential equation models

Summary The influence of spatial distribution pattern on the outcomes of intra- and interspecific competition is studied theoretically. The models developed are the generalized logistic andVolterra equations, whereLloyd’s indices of intra- and interspecies mean crowding were incorporated with their assumed linear relationship to mean density in order to express the intensity of crowding which is really effective to the existing individuals. It is shown that while the increasing patchiness of distribution has a pronounced effect of promoting the intraspecific competition and lowering the equilibrium density for individual populations, it generally relaxes the interspecific competition, making it easy for different species sharing the same niche, which would otherwise be incompatible, to coexist stably. These models thus provide a simplest theoretical basis to explain why many insect populations in nature are kept relatively rare in number and why a number of allied species often coexist freely sharing the same resource, against the “competitive exclusion principle” deduced from the originalVolterra equations.     

Predictability,complexity, and catastrophe in a collapsible model of population,development, and environmental interactions

"More and more population forecasts are being produced with associated 95 percent confidence intervals. How confident are we of those confidence intervals? In this paper, we produce a simulated dataset in which we know both past and future population sizes, and the true 95 percent confidence intervals at various future dates. We use the past data to produce population forecasts and estimated 95 percent confidence intervals using various functional forms. We, then, compare the true 95 percent confidence intervals with the estimated ones. This comparison shows that we are not at all confident of the estimated 95 percent confidence intervals." (SUMMARY IN FRE)     

Exploring relationships between sexual orientation and satisfaction with faculty and staff interactions

Lesbian, gay, and bisexual (LGB) students are a unique population within colleges and universities, yet, few studies have sought to uncover the distinctive environmental influences and background characteristics that foster their satisfaction. The purpose of this study was to examine the relationship between sexual orientation and a sense of satisfaction with faculty and staff interactions among undergraduate students. Analysis of variance results indicated that LGB students, on average, reported significantly higher satisfaction with faculty and staff interactions than heterosexual students. Using Astin's (1993 ) input-environments-outcome model as a conceptual framework, the hierarchical regression analysis yielded numerous significant variables as predictors for student satisfaction with faculty and staff interactions.     

Gay men and lesbians' experiences in and expectations for interactions with heterosexuals

We analyzed 97 gay men's and lesbians' experiences with and expectations for interactions with majority group members. Respondents described reactions to previous or imagined future interactions with an unfamiliar heterosexual person who had just become aware that the respondent was lesbian or gay. Results indicated that respondents are more proactive than reactive (in contrast to expectation states theories), that the contact hypothesis can be appropriately applied to this group, even though the formulation of the theory was based upon negative attitudes in the absence of extensive contact, and that they have different reactions for people of different prejudice levels, rather than being globally suspicious, as is predicted by many intergroup theories. Future research should direct more attention to the stigmatized group members' attitudes about and reactions toward the majority group.     

Time preference and capital mobility in an OLG model with land

This paper examines the pattern of capital mobility in a two-country overlapping generations world in which production uses three inputs: capital, labor and land. The steady-state welfare consequences of opening countries to financial capital or labor mobility are then compared. In particular, it is shown that capital mobility does not equalize standards of living across countries. To achieve this goal, one has to rely on labor mobility. Received: 8 January 1996 / Accepted: 6 June 1996     

A collective model for female labour supply with non-participation and taxation

This paper presents a collective discrete-choice model for female labour supply. Preferences of females and the intra-household allocation process are both econometrically identified. The model incorporates non-participation and non-linear taxation. It is applied to Belgian micro-data and is used to evaluate two revenue-neutral versions of the 2001 Tax Reform Act. We find small positive behavioural responses to the reforms. The reforms are not unambiguously welfare-improving. Generally, the first revenue-neutral reform (the actual reform and a household lump-sum tax) is more beneficial to females in couples than the second (the actual reform and a proportional decrease of household disposable incomes).

The labour supply of Indigenous Australian females: the effects of fertility and interactions with the justice system

Indigenous females are among the most disadvantaged groups in Australia; Furthermore outcomes for Indigenous Australians compare unfavourably with those for similar First Nations around the world. There appears to be a demographic transition under way in Indigenous Australia whereby declines in fertility and mortality are likely to lead to an increase in the number of Indigenous people supplying their labour in the near future. This paper examines the determinants of Indigenous female labour force participation with a particular focus on the role of fertility and interaction with the justice system. The analysis controls for the standard determinants of labour supply, but its main contribution is in taking into account the endogeneity of these potential interruptions to labour market participation. These findings are also important because Indigenous Australian females are 22 times more likely to be in prison than other Australian females and hence the analysis has crucial implications for the ability of policy makers to ‘close the gaps’ between Indigenous and other Australians. Once endogeneity of fertility with labour supply is taken into account, there is no significant independent effect on labour force participation and hence policy should focus on the other factors including education and training.     

两种户籍身份外来人口及其社会医疗保障获得

本文通过对农业人口和非农业人口两种户籍身份的外来人口在流入地城市的社会医疗保险获得的比较发现,代表着城乡分割体制因素的户籍差异已不是影响他们获得社会医疗保险的决定性因素,另一个制度变量——合同的签订,正在取代户籍制度发生着作用。这也意味着城乡分割的分析框架开始具有一定的局限性,对外来人口社会保障获得的研究需要进一步开阔视野,寻找一些城乡分割因素之外的原因。     

Time preference and labour migration in an OLG model with land and capital

This paper constructs a two-country migration model in the lines of Galor (1986), in which the world population consists of individuals of two types who have different time preferences. Production uses three inputs: mobile labour, immobile capital and land. It is shown that both countries are necessarily inhabited by agents of both types and exhibit equal density of population and equal interest rate at the steady state equilibrium of the integrated economy. The steady state welfare implications of international labour migration are studied.This paper has been written during Philippe Michel's visit at CORE, September 1994. Earlier drafts of this paper have been presented at the meeting Journées d'étude générations imbriquées (Marseille, November 24–26, 1994), at the ESPE conference (Lisbon, June 1–3, 1995) and at the EEA annual meeting (Prag, September 1–3, 1995). Comments by participants are gratefully acknowledged. We are also grateful to Stéphane Déo, Kamhon Kan, Pierre Pestieau, Christoph Schmidt and two anonymous referees for helpful comments. The usual disclaimer applies.Responsible editor: Alessandro Cigno     

A simple endogenous growth model with endogenous fertility: indeterminacy and uniqueness

This paper studies the equilibrium dynamics and indeterminacy of equilibria in an endogenous growth model with endogenous fertility choice. We characterize the conditions that give rise to an unique equilibrium as well as multiple equilibria. Whenever there exists a unique equilibrium, it will be globally determinate; when multiple equilibria arise, indeterminacy occurs. In particular, we find that two equilibria occur – one is associated with high fertility and low growth, while the other is associated with low fertility and high growth. A parameterized example is given to assess the empirical feasibility of our results. The validity of the neo-Malthusian relation between fertility and growth is then re-examined. Finally, we study the relation between growth and welfare and compare different balanced growth equilibria in terms of their lifetime-attained utility. JEL classifications: O41, J13 Received December 11, 1995 / Accepted October 20, 1996     

An analytic simulation model of human reproduction with demographic and biological components

Abstract This Monte Carlo model for simulating the reproductive history of a cohort of women is described in detail. The model provides for patterns of survival, sterility, formation and dissolution of sexual unions, fecundability, lactation, foetal wastage, family planning practices etc. Natality indices specific for marital status, for duration of marriage and for age, as well as analyses of birth spacing patterns are among the results that may be obtained. In the model, the experimental unit is an individual woman. The complete life history of a woman is generated and recorded before the history of the next woman is generated. The data for the whole cohort are analyzed at the end of the programme. The model includes two kinds of states into which a woman may pass, namely: (1) permanent changes of status such as death, sterility, or becoming a family planner, and (2) temporary states, each with a probability distribution of length of stay. The probabilities of the various events or changes of state may vary from age, parity, and other features of a woman's status or history. Natural fecundability at any age may also vary from woman to woman. In this programme natality patterns and specific indices such as age-specific fertility rates are produced, in a quasi-realistic fashion, by the interplay of the demographic and biological parameters postulated for any cohort. Consequently, the effect of changes in anyone factor can be studied, as well as the interaction resulting from changes in several factors. The purposes and potentials of the model are both substantive and methodological. As an illustration, a series of computer runs attempting to simulate the reproductive patterns of Indian women is presented. These results, as well as some additional ones, indicate some effects of changes in marital patterns, levels of fecundability, duration of post-partum non-susceptibility, age incidence of sterility and foetal wastage. In the final section of the paper, the advantages and possible applications of the model are discussed together with the limitations encountered to date in the efforts to apply the model.     

Ergodicity and extinction in a stochastic susceptible-infected-recovered-susceptible epidemic model with influence of information

An epidemic model with stochastic contact transmission coefficient takes into account white noise and the influence of information. Sufficient conditions for the extinction and persistence of the disease are expressed. The existence of a stationary distribution and the ergodic property are proved. The peak of infected population can be decreased by information. The analytical results are showed by simulations and the influence of white noise and information on the dynamics of epidemics are evaluated.     

Univoltine and bivoltine life cycles in insects: A model with density-dependent selection

Summary Selection for univoltine and bivoltine life cycles in insects under resource-limited but favourable temperature conditions is analyzed with a difference equation model including density-dependent population dynamics based on the conceptual framework of an evolutionarily stable strategy. The model predicts that the bivoltine type can spread in a univoltine population when the fraction of density-independent rate of annual increase by producing a second generation exceeds the survival rate during diapause of the univoltine type, but monopoly of the bivoltine type is not possible unless it attains an equilibrium population density exceeding that of the univoltine type. The applicability of the model prediction in explaining the occurrence of a partial bivoltine cycle in predominantly univoltine population in the temperate zones is discussed.     

A measure of sexual selection for interspecific comparisons of species with diversified mating systems and different mortality schedules

Summary Based on variances in components of lifetime reproductive success (LRS), a new index of the intensity of sexual selection was proposed mainly useful for interspecific comparisons. The index was defined as the male to female ratio of the standardized variance in mating efficiency during mating period. The index can to a large extent exclude the effect from natural selection which commonly act on both sexes in mating period and also from mortality in pre-reproductive period. This empirical measure has some defects in the strict sense (i.e., dichotomy of natural and sexual selection), however, it enables interspecific comparisons of the intensity of sexual selection among different taxonomic groups of animals with various mating systems and mortality schedules.     

Spatial variation in female fertility related to interactions with flower consumers and pathogens in a forest metapopulation ofPrimula sieboldii

Antagonistic biological interactions with flower consumers and pathogens may influence reproductive success of flowering plants, affecting population dynamics and natural selection for floral traits. However, ecological and evolutionary consequences of the interactions may depend on both spatial and temporal patterns of the interactions. In a forest metapopulation ofPrimula sieboldii E. Morren, an endangered clonal plant species, we measured between-subpopulation patterns of seed sets and interactions with an influential flower consumer, a rove beetle,Eusphalerum bosatsu Watanabe, and a specific smut fungal pathogen,Urocystis tranzschelina (Lavrov) Zundel (Ustilaginales), for three years. Mean female fertility (seed set per flower) for individual subpopulations fluctuated moderately among years but was highly variable within each year among the five subpopulations studied. In two subpopulations, the impact ofEusphalerum beetle, was sufficiently large to result in almost complete failure in seed production over eight years including the three study and five previous preliminary observation years. In the two other subpopulations, seed set failure was caused by infection by the smut fungus. Infected capsules which constitute 10–30% of the capsules produced in the subpopulations were filled with ustilospores instead of seeds. In the subpopulation that escaped flower damage byEusphalerum beetles and smut fungal infection, seed sets of both pin and thrum flowers were much higher than in the other subpopulations. The spatial restriction of individual antagonistic agents to a part of subpopulations suggest that dispersal of the agents, as well as the mode of spatial subdivision of the plant population would be important for determining the overall effects of antagonistic interactions on plant performances at the metapopulation level.     

Labor immigration and long-run welfare in a growth model with heterogenous agents and endogenous labor supply

This paper examines the consequences of labor immigration in an OLG economy in which agents have an elastic labor supply and differ with respect to degrees of altruism and rates of time preference. It focuses on three substantive questions. First, how do immigrants influence the bequest motive of altruistic natives? Second, what impact do immigrants have on the labor supply of natives? Finally, how does immigration affect the long-run welfare of both altruistic and non altruistic natives? Received: 25 November 1999/Accepted: 07 April 2000     

Physical capital taxation and labor income taxation in an endogenous growth model with new generations

This paper examines the growth and welfare effects of physical capital taxation and labor income taxation. It is found that the impact of a rise in the physical capital tax rate on the balanced growth rate is crucially related to the birth rate, but a rise in the labor income tax rate definitely reduces the balanced growth rate regardless of the birth rate. It is also found that an increase in the physical capital income tax rate will harm the older but will benefit the younger, while an increase in the labor income tax rate will benefit the older but will harm the younger.