On-line bin packing with restricted repacking

Semi-on-line algorithms for the bin-packing problem allow, in contrast to pure on-line algorithms, the use of certain types of additional operations for each step. Examples include repacking, reordering or lookahead before packing the items. Here we define and analyze a semi-on-line algorithm where for each step at most k items can be repacked, for some positive integer k. We prove that the upper bound for the asymptotic competitive ratio of the algorithm is a decreasing function of k, which tends to 3/2 as k goes to infinity. We also establish lower bounds for this ratio and show that the gap between upper and lower bounds is relatively small.     

Multivariate log-Birnbaum–Saunders regression models

In this paper, we present a multivariate version of the skewed log-Birnbaum–Saunders regression model. This new family of distributions holds good properties such as marginal variables following univariate skewed log-Birnbaum–Saunders distributions, besides presenting the usual log-Birnbaum–Saunders distribution as a particular case. Furthermore, the model parameters are estimated through maximum-likelihood methods, a closed-form expression for the Fisher’s information matrix is presented, and testing hypothesis for model parameters is performed. Two real datasets are analyzed and results are discussed.     

Multigaussian models: The danger of parsimony

Summary MultiGaussian models have the intrinsic property of imposing very little continuity to extreme values. If the variable that is being modeled is hydraulic conductivity and the processes being studied are groundwater flow and mass transport, the absence of continuous paths of extreme values will have a retardation effect in the computed travel times. In the case of radionuclide release of nuclear waste from a deep geological repository, underestimation of travel times may lead to unsafe decision making. To demonstrate the impact of the low continuity of extreme value implicit to multiGaussian modes, travel times are computed in a site similar to Finnsj?n-one of the sites in crystaline rock studied in Sweden-using two stochastic models with the same histogram and covariance, one of them is multiGaussian, and the other is not and displays high connectivity of extreme high values. The results show that the multiGaussian model leads to less conservative results than the non-multiGaussian one. Invoking the parisimony principle to select a multiGaussian model as the simplest model that can be fully described by a mean value and a covariance function should not be justification enough for such selection. If there is not enough data to characterize the connectivity of the extreme values and therefore distriminate whether a multiGaussian model is appropriate or not, less parismonious models must also be considered.     

The time budget in socio-demographic statistics

The paper describes a Polish time budget survey conducted in 1976 on a rotation sample of the whole (non-agricultural and agricultural) adult population. Different time budget indicators are presented and their linkages with other statistical data and usefulness for social policy formulation and evaluation are discussed. Some new time indicators, not used in previous surveys, are recommended. Usefulness of time budged surveys for assessing an account of labor force and investigating of the social distribution of labor time as well as leisure time is underlined. The possibility of using time budget data for analyses of the social distribution of some welfare outlays in the field of cultural participation and consumption is also indicated. The paper is concerned with some methodological problems and the applicability of time budget research, rather than a comprehensive presentation of survey results.     

Note on the Cramér-Rao inequality in the nonregular case: the family of uniform distributions

We consider the family of uniform distributions with range of unit length. The main result of this note asserts that the average variance of any unbiased estimator of the midpoint of the range is not less than (2(n+1))(n+2))^-1 and this lower bound is sharp. The proof is based upon a nonregular version of the Cramér-Rao inequality.     

Demographic characteristics,work complexity and economic setting as social status determinants

Various aspects of social standing are significantly, though differently, determined by demographic characteristics, by employment in different economic sectors and industries, and by work complexity. Various sectors and industries influence differently status achievement, and are characterized by different configurations of status determinants of their workforces. The public (government) sector is more meritocratic than the private one, as far as income is concerned. Also, the male achievement pattern seems to be more meritocratic, while the female pattern is more sensitive to transient influences. The indicators of socio-economic status, occupational prestige and income reflect separate dimensions of social standing. The indicators of work complexity with data, people and things are good predictors of individual's social position.     

Shorter hours wanted? A systematic review of working-time preferences and outcomes

Changes in working time have important economic, social and environmental implications. However, research on workers' preferences is highly fragmented across disciplines and journals. To overcome this, the present article provides a systematic review of the literature, analysing 173 studies. The study shows that working-time outcomes and mismatches are mostly studied in a small group of OECD countries, using survey data and statistical methods. The most clear and consistent results are about gender, care responsibilities and current working hours. Among professions, only the medical workforce receives substantial attention. Norms and preference formation are poorly understood, and more qualitative research is essential to understand how working-time reductions could spread.     

Objective Bayesian Analysis of an Exponential Regression Model with Constrained Parameters Applied to Animal Digestibility

In animal digestibility the proportion of degraded food along the time has usually been modeled as a normal random variable with mean a function of the time and the following three parameters: the proportion of degraded food almost instantaneously, remaining proportion of food to be degraded, and velocity of degradation. The estimation of these parameters has been carried out mainly from a frequentist viewpoint by using the asymptotic distribution of the maximum likelihood estimator. This may give inadmissible estimates, such as values outside of the range of the parameters. This drawback could not appear if a Bayesian approach were adopted. In this article an objective Bayesian analysis is developed and illustrated on real and simulated data.     

The Poisson-conjugate Lindley mixture distribution

ABSTRACT

A new discrete distribution that depends on two parameters is introduced in this article. From this new distribution the geometric distribution is obtained as a special case. After analyzing some of its properties such as moments and unimodality, recurrences for the probability mass function and differential equations for its probability generating function are derived. In addition to this, parameters are estimated by maximum likelihood estimation numerically maximizing the log-likelihood function. Expected frequencies are calculated for different sets of data to prove the versatility of this discrete model.