On the estimation of the most probable number in a serial dilution experiment

The purpose of this paper is to present some alternative estimates for the 'most probable number' of bacteria in a serial dilution experiment. These estimates are directed to be less biased than the ordinary maximum likelihood estimate. A numerical example illustrates the extent to which the variance and the mean square error of these estimates are generally less than those corresponding to the maximum likelihood estimate.     

The Dynamic Relationship Between the Dollar and Components of U.S. Trade

The dynamic response of the nominal trade account to changes in the value of the U.S. dollar has been posited to follow a J-curve pattern. Recent experience calls this into question. The aggregate nominal trade balance is decomposed here into four components, both prices and volumes of imports and exports. Time series specification tests and Granger tests of causal priority are employed to identify the existence and nature of the response of each individual component to dollar movements. Surprisingly weak and delayed responses of both import prices and volumes are found, suggesting a new view of trade-balance evolution.     

A note on the analysis of parity progression ratios

Contingency table modeling procedures are proposed to examine the effects of independent variables on parity progression ratios. The methodology is outlined and an incremental-factorial linear model is developed.     

Developing human resource competencies: an empirical evidence

The paper conceptually defines and empirically investigates the density of work experience along with individual characteristics (cognitive ability, Conscientiousness, and Openness to Experience) and examine their influence on Human Resource (HR) competencies. 274 HR executives from diverse industry background and their supervisors participated in the data collection efforts spread over three phases. Data analyses revealed three key findings (i) executives’ density of work experience positively relates to HR competencies, (ii) executives’ cognitive ability is the strongest predictor of the positive relationship to HR competencies, and (iii) executives with high Conscientiousness tend to achieve levels of density of work experience. Relative weight analyses reinforce that cognitive ability and density of work experience are the most prominent predictors of HR competencies. Implications for practice are discussed.     

Use of generalized estimating equations in a trial in influenza to explore treatment effects over time

For trials with repeated measurements of outcome, analyses often focus on univariate outcomes, such as analysis of summary measures or of the last on‐treatment observation. Methods which model the whole data set provide a rich source of approaches to analysis. For continuous data, mixed‐effect modelling is increasingly used. For binary and categorical data, models based on use of generalized estimating equations account for intra‐subject correlation and allow exploration of the time course of response, as well as providing a useful way to account for missing data, when such data can be maintained as missing in the analysis. The utility of this approach is illustrated by an example from a trial in influenza. Copyright © 2004 John Wiley & Sons Ltd.     

The Equivalence of Parameter Estimates from Growth Curve Models and Seemingly Unrelated Regression Models

Seemingly unrelated regression models and growth curve models are examples of multivariate models that require special estimation techniques. Parameters in seemingly unrelated regression models can be estimated by using two-stage Aitken estimation based on unrestricted residuals; parameters in growth curve models can be estimated by using a Potthoff-Roy (1964) transformation based on an estimate of the dispersion. With proper choice of the seemingly unrelated regression model, the two multivariate models and corresponding parameter estimates are shown to be equivalent. Recognition of the equivalence simplifies the presentation of these more complicated multivariate models. The connection is also of interest for more flexible growth curve models.     

From Poverty Reduction to Mutual Interests? The Debate on Differentiation in EU Development Policy

Aid to middle‐income countries has become one of the most discussed issues among development researchers and in the current modernisation of the development policy of the European Union. This article argues that the question needs to be dealt with in the context of two interlinked challenges: (i) the need to reconceptualise dominant approaches to global poverty reduction beyond national income, and (ii) the growing range of global challenges and the strategically important role of middle‐income countries. For EU development policy, the implications are twofold: (i) a better‐co‐ordinated cross‐country division of labour, and (ii) a diversification of objectives towards a global rationale of development policy involving closer co‐ordination with other EU external policies.     

THE EFFECT OF YOUTH ALCOHOL INITIATION ON HIGH SCHOOL COMPLETION

The social environment inherent in schools impacts both alcohol consumption onset and high school completion. The results reported here, based on data from the 1979–96 NLSY panels, show that the social coincidences between alcohol consumption and education are important determinants of both education completion and alcohol onset. Ignoring the social nature of these simultaneous decisions underestimates the impact of alcohol onset on education. After correcting for the presence of an endogenous positive relationship between schooling and alcohol consumption, we find that alcohol initiation before age 14 significantly reduces the probability of timeously completing high school by between 7% and 22%. (JEL I18 , I21 )