Marginalized zero-inflated generalized Poisson regression

The generalized Poisson (GP) regression model has been used to model count data that exhibit over-dispersion or under-dispersion. The zero-inflated GP (ZIGP) regression model can additionally handle count data characterized by many zeros. However, the parameters of ZIGP model cannot easily be used for inference on overall exposure effects. In order to address this problem, a marginalized ZIGP is proposed to directly model the population marginal mean count. The parameters of the marginalized zero-inflated GP model are estimated by the method of maximum likelihood. The regression model is illustrated by three real-life data sets.     

Sector Programme Approaches: Will They Work in Agriculture?

This article explores why sector‐wide approaches, in which donor funds support a single sector plan under government leadership, have performed less well in agriculture than in the social sectors. Many problems stem from the more limited, more contested and shrinking role of the state in the agricultural sector. It is also argued that sector programmes have worked best where the key constraints on sector development are the responsibility of a single ministry, whereas agricultural development requires co‐ordinated interventions across sectors. The sector approach may have a limited role in delivering better focused agricultural services, but fundamental policy questions need to be resolved first. This is more likely if support for reforms is channelled through central economic ministries and other bodies outside the agriculture ministry.     

Ökologische Validität durch Mixed-Methods-Designs

Due to their focus on variable-oriented comparisons and large-N samples, survey methods are prone to lack information on the context-specific, practical meaning of measured constructs. This issue is explicated via the concept of “ecological validity”. A sequential quantitative-qualitative mixed-methods-study on anti-American prejudice in Germany is presented to demonstrate how semi-structured qualitative interviews (n = 22) can compensate for lacking ecological validity in standardized prejudice measurements (CATI-survey, n = 808, summer 2011). Qualitative analyses provide context-sensitive insight into the rhetorical functions of anti-American speech. They are used to generate explanatory hypotheses for correlations between anti-American, anti-Semitic, and racist prejudice in the survey data. This complementarity of research methods is closely connected to an enhanced theoretical perspective: The combination of attitude-based and speech-act-theoretical concepts of prejudice helps to increase construct validity in the example study.     

Approximate Generalizations and Computational Experiments

In this paper I demonstrate how one can generalize finitely many examples to statements about (infinite) classes of economic models. If there exist upper bounds on the number of connected components of one‐dimensional linear subsets of the set of parameters for which a conjecture is true, one can conclude that it is correct for all parameter values in the class considered, except for a small residual set, once one has verified the conjecture for a predetermined finite set of points. I show how to apply this insight to computational experiments and spell out assumptions on the economic fundamentals that ensure that the necessary bounds on the number of connected components exist. I argue that these methods can be fruitfully utilized in applied general equilibrium analysis. I provide general assumptions on preferences and production sets that ensure that economic conjectures define sets with a bounded number of connected components. Using the theoretical results, I give an example of how one can explore qualitative and quantitative implications of general equilibrium models using computational experiments. Finally, I show how random algorithms can be used for generalizing examples in high‐dimensional problems.     

Basic Wages and Firm Characteristics: Rent Sharing in French Manufacturing

Abstract. This paper shows that firm profits (and losses), and value added, are strongly related to individual hourly basic wages for most employees, as well as to the total earnings measures used previously but correlated with working time. Capital intensity is independently important without reducing the significance of profits, as in other studies. Value added avoids the negative bias implicit in accounting profits, and has a much larger effect on basic wages and earnings in the presence of numerous individual and firm controls.     

Stationary Equilibria in Asset‐Pricing Models with Incomplete Markets and Collateral

We consider an infinite‐horizon exchange economy with incomplete markets and collateral constraints. As in the two‐period model of Geanakoplos and Zame (2002), households can default on their liabilities at any time, and financial securities are only traded if the promises associated with these securities are backed by collateral. We examine an economy with a single perishable consumption good, where the only collateral available consists of productive assets. In this model, competitive equilibria always exist and we show that, under the assumption that all exogenous variables follow a Markov chain, there also exist stationary equilibria. These equilibria can be characterized by a mapping from the exogenous shock and the current distribution of financial wealth to prices and portfolio choices. We develop an algorithm to approximate this mapping numerically and discuss ways to implement the algorithm in practice. A computational example demonstrates the performance of the algorithm and shows some quantitative features of equilibria in a model with collateral and default.     

Protective indigenous collective value of Ubuntu and child neglect: Implications for rural child protection practice

Theories on collective efficacy and social support suggest that indigenous values that support collective practices and sanction community obligations to childcare would be protective against child neglect. Likewise, new qualitative findings show that collective values are stronger in rural areas than in urban. This study tested the claims that the value of Ubuntu, which is a symbolic cultural value of ‘being for others’, will be protective against the likelihood of neglect; this relationship will be stronger in rural compared with urban communities in Ghana. Using data obtained from a nationally representative sample of 1100 mothers (from 22 communities) in Ghana, we tested the claims using fixed effects logistic regression. The Ubuntu norms were significantly endorsed in rural communities compared with the urban. The overall model showed that higher levels of Ubuntu are associated with lower odds of child neglect (OR .47, [.29, .76] p < 0.05), and the relationship remained significant only in the rural sample (OR .13, [.06, .31] p < 0.001). Similar evidence was recorded for the Ubuntu norms of community care and compassion. The results suggest that child protection in rural Ghana can be fruitful when interventions are developed to boost the value of Ubuntu and the norms of collective childcare.     

On the bivariate negative binomial regression model

In this paper, a new bivariate negative binomial regression (BNBR) model allowing any type of correlation is defined and studied. The marginal means of the bivariate model are functions of the explanatory variables. The parameters of the bivariate regression model are estimated by using the maximum likelihood method. Some test statistics including goodness-of-fit are discussed. Two numerical data sets are used to illustrate the techniques. The BNBR model tends to perform better than the bivariate Poisson regression model, but compares well with the bivariate Poisson log-normal regression model.     

Characterization of dominance relations in finite coalitional games

McGarvey (Econometrica, 21(4), 608–610, 1953) has shown that any irreflexive and anti-symmetric relation can be obtained as a relation induced by majority rule. We address the analogous issue for dominance relations of finite cooperative games with non-transferable utility (coalitional NTU games). We find any irreflexive relation over a finite set can be obtained as the dominance relation of some finite coalitional NTU game. We also show that any such dominance relation is induced by a non-cooperative game through β-effectivity. Dominance relations obtainable through α-effectivity, however, have to comply with a more restrictive condition, which we refer to as the edge-mapping property.