A Smoothed-Distribution Form of Nadaraya-Watson Estimation

Given observation-pairs (xi ,yi ), i = 1,...,n , taken to be independent observations of the random pair (X ,Y), we sometimes want to form a nonparametric estimate of m(x) = E(Y/ X = x). Let YE have the empirical distribution of the yi , and let (XS ,YS ) have the kernel-smoothed distribution of the (xi ,yi ). Then the standard estimator, the Nadaraya-Watson form mNW(x) can be interpreted as E(YE?XS = x). The smoothed-distribution estimator ms (x)=E(YS/XS = x) is a more general form than  mNW (x) and often has better properties. Similar considerations apply to estimating Var(Y/X = x), and to local polynomial estimation. The discussion generalizes to vector (xi ,yi ).nonparametric regression, Nadaraya-Watson, kernel density, conditional expectation estimator, conditional variance estimator, local polynomial estimator

Wage Dispersion in a Partially Unionized Labor Force

Wage Dispersion in a Partially Unionized Labor Force This paper critiques Card’s (2001) method for analyzing wage dispersion in a partially unionized labor market based on a disaggregation of the population into skill categories. We argue that disaggregation is a good idea, the use of skill categories less so. We offer a modified model in which each worker is assigned a union-membership probability, a predicted union wage, and a predicted nonunion wage. Our model provides a natural three-way decomposition of variance, and is also suited to counterfactual analysis. By way of an application, we examine the effect of de-unionization on wage dispersion in the United Kingdom between 1983 and 1995, reporting that the decline in membership accounts for only about one-fifth of the observed increase in wage dispersion.wage dispersion, three-way variance decomposition, bivariate kernel density smoothing, union membership, deunionization.

Wage Dispersion in a Partially Unionized Labor Force

Taking as our point of departure a model proposed by David Card (2001), we suggest new methods for analyzing wage dispersion in a partially unionized labor market. Card's method disaggregates the labor population into skill categories, which procedure entails some loss of information. Accordingly, we develop a model in which each worker individually is assigned a union-membership probability and predicted union and nonunion wages. The model yields a natural three-way decomposition of variance. The decomposition permits counterfactual analysis, using concepts and techniques from the theory of factorial experimental design. We examine causes of the increase in U.K. wage dispersion between 1983 and 1995. Of the factors initially considered, the most influential was a change in the structure of remuneration inside both the union and nonunion sectors. Next in importance was the decrease in union membership. Finally, exogenous changes in labor force characteristics had, for most groups considered, only a small negative effect. We supplement this preliminary three-factorial analysis with a five-factorial analysis that allows us to examine effects from the wage-equation parameters in greater detail.wage dispersion, three-way variance decomposition, bivariate kernel density smoothing, union membership, deunionization, factorial experimental design

Multi-scale coarse-graining of diblock copolymer self-assembly: from monomers to ordered micelles

Starting from a microscopic lattice model, we investigate clustering, micellization and micelle ordering in semi-dilute solutions of AB diblock copolymers in a selective solvent. To bridge the gap in length scales, from monomers to ordered micellar structures, we implement a two-step coarse graining strategy, whereby the AB copolymers are mapped onto ``ultrasoft'' dumbells with monomer-averaged effective interactions between the centres of mass of the blocks. Monte Carlo simulations of this coarse-grained model yield clear-cut evidence for self-assembly into micelles with a mean aggregation number n of roughly 100 beyond a critical concentration. At a slightly higher concentration the micelles spontaneously undergo a disorder-order transition to a cubic phase. We determine the effective potential between these micelles from first principles.Comment: 4 pages, 4 figures, submitted to Phys. Rev. Lett

Building Blocks in the Economics of Mandates

The paper constructs an asymmetric information model to investigate the efficiency and equity cases for government mandated benefits. A mandate can improve workers' insurance, and may also redistribute in favour of more "deserving" workers. The risk is that it may also reduce output. The more diverse are free market contracts – separating the various worker types – the more likely it is that such output effects will on balance serve to reduce welfare. It is shown that adverse effects can be reduced by restricting mandates to larger firms. An alternative to a mandate is direct government provision. We demonstrate that direct government provision has the advantage over mandates of preserving separations.asymmetric information, labour mandates, compensation packages

Kinetics of Surfactant Adsorption at Fluid/Fluid Interfaces: Non-ionic Surfactants

We present a model treating the kinetics of adsorption of soluble surface-active molecules at the interface between an aqueous solution and another fluid phase. The model accounts for both the diffusive transport inside the solution and the kinetics taking place at the interface using a free-energy formulation. In addition, it offers a general method of calculating dynamic surface tensions. Non-ionic surfactants are shown, in general, to undergo a diffusion-limited adsorption, in accord with experimental findings.Comment: 6 pages, 3 figures, see also cond-mat/960814

Open data and smallholder food and nutritional security

This report was commissioned CTA as a member of the GODAN initiative. It aims to provide a better understanding of the actual impact of the open data movement on the food and nutrition security of smallholders and highlight the areas of potential unfilled opportunity

Wage dispersion in a partially unionized labor force

Taking as our point of departure a model proposed by David Card (2001), we suggest new methods for analyzing wage dispersion in a partially unionized labor market. Card's method disaggregates the labor population into skill categories, which procedure entails some loss of information. Accordingly, we develop a model in which each worker individually is assigned a union-membership probability and predicted union and nonunion wages. The model yields a natural three-way decomposition of variance. The decomposition permits counterfactual analysis, using concepts and techniques from the theory of factorial experimental design. We examine causes of the increase in U.K. wage dispersion between 1983 and 1995. Of the factors initially considered, the most influential was a change in the structure of remuneration inside both the union and nonunion sectors. Next in importance was the decrease in union membership. Finally, exogenous changes in labor force characteristics had, for most groups considered, only a small negative effect. We supplement this preliminary three-factorial analysis with a five-factorial analysis that allows us to examine effects from the wage-equation parameters in greater detail

Moxalactam Therapy for Obstetric and Gynecologic Infections

Moxalactam, a new cephalosporin antibiotic with a broad spectrum of activity, was evaluated for safety and therapeutic efficacy in the treatment of genital tract infections in women. Fifty-three patients with postpartum endometritis or acute or chronic pelvic inflammatory disease were treated with 2 g of moxalactam iv every 8 hr, usually for five days or longer. Appropriate cultures of peripheral blood, endometrium, cul-de-sac aspirates, urine, wound, and endocervix (only for Neisseria gonorrhoeae) were performed. Overall, 90.6% (48 of 53) of the patients were successfully treated with moxalactam - 86.2% (25 of 29) and 95.8% (23 of 24) of the patients with endometritis and pelvic inflammatory disease, respectively. Therapy failed in one of five bacteremic patients with endometritis. Of all the bacteria isolated from appropriate culture sites, 58% (224 of 383) were anaerobes, with anaerobic gram-negative rods - particularly Bacteroides bivius-and gram-positive cocci being predominant. Of 206 anaerobic strains tested with moxalactam by agar dilution techniques, 82% (169 of 206) were susceptible (minimal inhibitory concentration [MIC], ⩽8 μg/ml), 11.6% (24 of 206) were moderately susceptible (MIC, 16-32 μg/ml), and 6.3% (13 of 206) were resistant (MIC, ⩾64 μg/ml). Among the aerobic isolates, enterococci were uniformly resistant. Thus, moxalactam performed well as a single agent in this open clinical trail for women with infections of the genital trac

Worker participation and firm performance : evidence from Germany and Britain

This paper examines the Freeman-Lazear works council/worker involvement model against the empirical backdrop of two different industrial relations systems: the British voluntaristic system, and the German system of mandatory works councils. We find that in nonunion British firms worker involvement increases economic performance, but in the union firms there are negative effects. The implication is that local distributive conflict can cause the wrong level of worker involvement to be chosen, as predicted by the model. ln Germany, where centralized collective bargaining reduces local distributive conflict, we find that a mandate can be advantageous, again as predicted by the model. However, the straitjacket of a mandate is shown to disadvantage small German firms