Estimating a class of triangular simultaneous equations models without exclusion restrictions

This paper provides a control function estimator to adjust for endogeneity in the triangular simultaneous equations model where there are no available exclusion restrictions to generate suitable instruments. Our approach is to exploit the dependence of the errors on exogenous variables (e.g. heteroscedasticity) to adjust the conventional control function estimator. The form of the error dependence on the exogenous variables is subject to restrictions, but is not parametrically specified. In addition to providing the estimator and deriving its large-sample properties, we present simulation evidence which indicates the estimator works well.

Does increasing parents' schooling raise the schooling of the next generation? Evidence based on conditional second moments

This paper investigates the degree of intergenerational transmission ofeducation for individuals from the National Longitudinal Survey of Youth1979. Rather than identifying the causal effect of parental education viainstrumental variables we exploit the feature of the transmissionmechanism responsible for its endogeneity. More explicitly, we assume theintergenerational transfer of unobserved ability is invariant to the economicenvironment. This, combined with the heteroskedasticity resulting from theinteraction of unobserved ability with socioeconomic factors, identifies thiscausal effect. We conclude the observed intergenerational educationalcorrelation reflects both a causal parental educational effect and a transferof unobserved ability.Intergenerational mobility, endogeneity, conditional correlation

A Parametric Control Function Approach to Estimating the Returns to Schooling in the Absence of Exclusion Restrictions: An Application to the NLSY

We estimate the return to education using a sample drawn from the National Longitudinal Survey of Youth 1979 (NLSY79). Rather than accounting for the endogeneity of schooling through the use of instrumental variables we employ a parametric version of the Klein and Vella (2006a) estimator. This estimator bypasses the need for instruments by exploiting features of the conditional second moments of the errors. As the Klein and Vella (2006a) procedure is semi-parametric it is computationally demanding. We illustrate how to greatly reduce the required computation by parameterizing the second moments. Accounting for endogeneity increases the estimate of the return to education by 5 percentage points, from 7.6% to 12.7%.return to education, heteroskedasticity, endogeneity

Does Increasing Parents' Schooling Raise the Schooling of the Next Generation? Evidence Based on Conditional Second Moments

This paper investigates the degree of intergenerational transmission of education for individuals from the National Longitudinal Survey of Youth 1979. Rather than identifying the causal effect of parental education via instrumental variables we exploit the feature of the transmission mechanism responsible for its endogeneity. More explicitly, we assume the intergenerational transfer of unobserved ability is invariant to the economic environment. This, combined with the heteroskedasticity resulting from the interaction of unobserved ability with socioeconomic factors, identifies this causal effect. We conclude the observed intergenerational educational correlation reflects both a causal parental educational effect and a transfer of unobserved ability.intergenerational mobility, endogeneity, conditional correlation

Subjective Health Assessments and Active Labor Market Participation of Older Men: Evidence from a Semiparametric Binary Choice Model with Nonadditive Correlated Individualspecific Effects

We use panel data from the US Health and Retirement Study 1992-2002 to estimate the effect of self-assessed health limitations on active labor market participation of men around retirement age. Self-assessments of health and functioning typically introduce an endogeneity bias when studying the effects of health on labor market participation. This results from justification bias, reflecting an individual’s tendency to provide answers which "justify" his labor market activity, and individual-specific heterogeneity in providing subjective evaluations. We address both concerns. We propose a semiparametric binary choice procedure which incorporates potentially nonadditive correlated individual-specific effects. Our estimation strategy identifies and estimates the average partial effects of health and functioning on labor market participation. The results indicate that poor health and functioning play a major role in the labor market exit decisions of older men.

A Parametric Control Function Approach to Estimating the Returns to Schooling in the Absence of Exclusion Restrictions: An Application to the NLSY

An innovation which bypasses the need for instruments when estimating endogenous treatment effects is identification via conditional second moments. The most general of these approaches is Klein and Vella (2010) which models the conditional variances semiparametrically. While this is attractive, as identification is not reliant on parametric assumptions for variances, the non-parametric aspect of the estimation may discourage practitioners from its use. This paper outlines how the estimator can be implemented parametrically. The use of parametric assumptions is accompanied by a large reduction in computational and programming demands. We illustrate the approach by estimating the return to education using a sample drawn from the National Longitudinal Survey of Youth 1979. Accounting for endogeneity increases the estimate of the return to education from 6.8% to 11.2%.return to education, heteroskedasticity, endogeneity

Waggle dance distances as integrative indicators of seasonal foraging challenges

Even as demand for their services increases, honey bees (Apis mellifera) and other pollinating insects continue to decline in Europe and North America. Honey bees face many challenges, including an issue generally affecting wildlife: landscape changes have reduced flower-rich areas. One way to help is therefore to supplement with flowers, but when would this be most beneficial? We use the waggle dance, a unique behaviour in which a successful forager communicates to nestmates the location of visited flowers, to make a 2-year survey of food availability. We “eavesdropped” on 5097 dances to track seasonal changes in foraging, as indicated by the distance to which the bees as economic foragers will recruit, over a representative rural-urban landscape. In year 3, we determined nectar sugar concentration. We found that mean foraging distance/area significantly increase from springs (493 m, 0.8 km2) to summers (2156 m, 15.2 km2), even though nectar is not better quality, before decreasing in autumns (1275 m, 5.1 km2). As bees will not forage at long distances unnecessarily, this suggests summer is the most challenging season, with bees utilizing an area 22 and 6 times greater than spring or autumn. Our study demonstrates that dancing bees as indicators can provide information relevant to helping them, and, in particular, can show the months when additional forage would be most valuable

Limitation of shipowners' liability

Consideration is given firstly to the origins of the principle of a shipowner being entitled to limit his liability to third parties who have suffered loss or injury as a result of the negligent navigation or management of his ship noting that the principle evolved as a matter of public policy designed to encourage shipping and trade. The various attempts at reaching international unity are then reviewed by way of reference to the 1924, 1957 and 1976 Conventions on Limitation of Shipowners' Liability including comment on the separate limitation regimes introduced by the Hague and Hague-Visby Rules in respect of the carriage of goods by sea. e the adoption of the principle of limitation into the South African law with the coming into force as at 1960 of the Merchant Shipping Act is then considered, it being noted here that the relevant provisions of No. 57 of 1951 reflect, rather than repeat the (then) corresponding provisions in the English law following on the adoption and enactment by that country of the 1957 Limitation Convention. The word reflect is used advisedly as South Africa is neither a signatory to nor has it adopted the 1957 Convention per se resulting in a measure of uncertainty and difficulty when it comes to the application of the relevant provisions of the Act. These provisions viz. s 261 et seq are then dealt with in some detail with consideration being given to such matters as to who may limit their liability, what ships are subject to limitation, the amounts of limitation and how these are. calculated with reference to a ship's tonnage etc. e Finally under this Part, the question of which claims are subject to limitation and which, by way of separate legislative enactment, are not subject to limitation, is examined. PART B: Pages 21 to 42 This Part is devoted to the loss of the right to limit liability with an in-depth look being taken at the meaning of the words "actual fault or privity". Here particular attention is paid to the interpretation of the personalised requirement of s 261 (whose actual fault or privity are we concerned with etc.?) and what degree of culpability the words connote. Given the dearth of reported South African cases, the approach of van Heerden Jin The "SAINT PADARN", 1986 ( being the only South African case to date dealing with the subject) is followed by way of having regard to a number of the leading English cases commencing with Lennard's case of 1915 through the well-known "LADY GWENDOLEN" case of 1965 and the "new approach" introduced. by it and beyond to the House of Lords decision in the "MARION", 1984

HUD student work-study program

Issued as monthly report [1]-15/16 (formerly E-17-502

The influence of the English Gothic romance on the novels of Charles Brockden Brown

This item was digitized by the Internet Archive. Thesis (M.A.)--Boston Universityhttps://archive.org/details/theinfluenceofen00dic