What is a problem?

Among others, the term “problem” plays a major role in the various attempts to characterize interdisciplinarity or transdisciplinarity, as used synonymously in this paper. Interdisciplinarity (ID) is regarded as “problem solving among science, technology and society” and as “problem orientation beyond disciplinary constraints” (cf. Frodeman et al.: The Oxford Handbook of Interdisciplinarity. Oxford University Press, Oxford, 2010). The point of departure of this paper is that the discourse and practice of ID have problems with the “problem”. The objective here is to shed some light on the vague notion of “problem” in order to advocate a specific type of interdisciplinarity: problem-oriented interdisciplinarity. The outline is as follows: Taking an ex negativo approach, I will show what problem-oriented ID does not mean. Using references to well-established distinctions in philosophy of science, I will show three other types of ID that should not be placed under the umbrella term “problem-oriented ID”: object-oriented ID (“ontology”), theory-oriented ID (epistemology), and method-oriented ID (methodology). Different philosophical thought traditions can be related to these distinguishable meanings. I will then clarify the notion of “problem” by looking at three systematic elements: an undesired (initial) state, a desired (goal) state, and the barriers in getting from the one to the other. These three elements include three related kinds of knowledge: systems, target, and transformation knowledge. This paper elaborates further methodological and epistemological elements of problem-oriented ID. It concludes by stressing that problem-oriented ID is the most needed as well as the most challenging type of ID.     

Incentive effects and the income tax treatment of employer-provided workplace benefits

Employers often provide their employees with different kinds of benefits in the workplace to create comfortable working conditions. In order to avoid distortions of the wage-benefit ratio in employee compensation, economic theory suggests that fringe benefits should be subject to income taxation at a value placed on them by employees. This article shows that this approach does not apply to workplace benefits. Since the goal of these benefits is to reduce the employees’ disutility from work, treating them simply as wage substitutes disregards their incentive effects. Therefore, the rules for taxing workplace benefits are derived from an agency model. It is shown that in contrast to the standard economic approach, cost can be a more efficient tax base than willingness to pay, even though this results in higher tax payments. Moreover, with non-distortionary tax rates it is always better to tax the employer rather than the employee.     

Estimating and comparing adverse event probabilities in the presence of varying follow-up times and competing events

Safety analyses of adverse events (AEs) are important in assessing benefit–risk of therapies but are often rather simplistic compared to efficacy analyses. AE probabilities are typically estimated by incidence proportions, sometimes incidence densities or Kaplan–Meier estimation are proposed. These analyses either do not account for censoring, rely on a too restrictive parametric model, or ignore competing events. With the non-parametric Aalen-Johansen estimator as the “gold standard”, that is, reference estimator, potential sources of bias are investigated in an example from oncology and in simulations, for both one-sample and two-sample scenarios. The Aalen-Johansen estimator serves as a reference, because it is the proper non-parametric generalization of the Kaplan–Meier estimator to multiple outcomes. Because of potential large variances at the end of follow-up, comparisons also consider further quantiles of the observed times. To date, consequences for safety comparisons have hardly been investigated, the impact of using different estimators for group comparisons being unclear. For example, the ratio of two both underestimating or overestimating estimators may not be comparable to the ratio of the reference, and our investigation also considers the ratio of AE probabilities. We find that ignoring competing events is more of a problem than falsely assuming constant hazards by the use of the incidence density and that the choice of the AE probability estimator is crucial for group comparisons.     

Survey of feral rock doves (Columba livia) in Amsterdam, a bird-human association

We carried out a survey of the feral rock doves (Columba livia) visible in the public areas of the fourteen Town Councils in Amsterdam. The objectives were to detect the preferential locations of the feral pigeons and to obtain reference values of their population sizes in order to be able to evaluate the effect of possible control measures. We registered 354 locations were twenty or more feral pigeons were visible during feeding. In these locations, averaged over ten to twelve counts, we counted 10,056 pigeons. Moreover we observed that at another 541 locations at least once five pigeons were visible during feeding. In all 894 locations we counted, averaged over four counts, 11,885 pigeons. By Town Council, we calculated strong positive correlations between the average number of pigeons per hectare, the human population density, the number of houses and the yearly number of kilos organic waste per hectare.     

Mixed contracts for the newsvendor problem with real options and discrete demand

In this paper we consider the newsvendor model with real options under discrete demand. We consider a mixed contract where the retailer can order a combination of q units subject to the conditions in a classical newsvendor contract and Q real options on the same items. We provide a closed form solution to this mixed contract when the demand is discrete and study some of its properties. In particular we demonstrate that a mixed contract may be superior to a real option contract when a manufacturer has a bound on how much variance she is willing to accept.     

On aggregation of strongly dependent time series

We consider cross-sectional aggregation of time series with long-range dependence. This question arises for instance from the statistical analysis of networks where aggregation is defined via routing matrices. Asymptotically, aggregation turns out to increase dependence substantially, transforming a hyperbolic decay of autocorrelations to a slowly varying rate. This effect has direct consequences for statistical inference. For instance, unusually slow rates of convergence for nonparametric trend estimators and nonstandard formulas for optimal bandwidths are obtained. The situation changes, when time-dependent aggregation is applied. Suitably chosen time-dependent aggregation schemes can preserve a hyperbolic rate or even eliminate autocorrelations completely.     

Not your lucky day: romantically and numerically special wedding date divorce risks

Characteristics of couples on or about their wedding day and characteristics of weddings have been shown to predict marital outcomes. Little is known, however, about how the dates of the weddings correlate with marriage durability. Using Dutch marriage and divorce registries from 1999 to 2013, this study compares the durations of marriages that began on unusually popular wedding dates with marriages on ordinary dates. We identify several distinct types of popular dates, including Valentine’s Day and numerically special days (dates with the same or sequential number values, e.g., 9.9.99, 1.2.03), showing that on an adjusted basis, the incidence of weddings on such dates was 137–509% higher than ordinary dates. The hazard odds of divorce for these special-date weddings were 18–36% higher than ordinary-date weddings. Sorting on couples’ observable characteristics accounts for some of the higher divorce risks, but even after controlling for these characteristics, special-date weddings were more vulnerable, with 10–17% higher divorce odds compared to ordinary dates. These relationships are even stronger for couples who have not married before.     

Statistically nonrepresentative stratified sampling: A sampling technique for qualitative studies

Summary When doing quantitative studies, we usually need a statistically representative sample. The same is often not the case with qualitative studies where we need a sample with variations along the independent variables. The technique described here is simple to use and guarantees variations. A statistically representative sample, on the other hand, if small, often gives few variations. Thus, one could say that the technique presented is a kind of statistically nonrepresentative stratified sampling useful in qualitative studies.The author wishes to thank the editors ofQualitiative Sociology for valuable comments and suggestions made on an earlier version of this note.     

Subset selection of superior populations when the number of populations is large

The situation where k populations are partitioned into one inferior group and one superior group is considered. The statistical problem is to select a random size subset of superior populations while trying to avoid including any inferior populations. A selection procedure is assumed to satisfy the condition that the probability of selecting at least one superior population is bounded below by P¹<1. The performance of a procedure is measured by the probability of including an inferior population.The asymptotic performance, as k→∞ of Gupta's traditional maximum type procedure ψ^G is considered in the location-model. For normally distributed populations, ψ^G turns out to be asymptotically optimal, provided the size of the inferior group does not become infinitely larger than the size of the superior group.     

Modern family initiation in sweden: Experience of women born between 1936 and 1960

This report investigates trends in the initial phases of the family-building process for Swedish women in five-year cohorts born between 1936 and 1960, using life-table techniques. Non-marital cohabitation was much more widespread in our pre-World War II cohort than has been realized previously. Among never-married women, first-birth fertility was remarkably stable for those in and those not in a consensual union alike. Strong increases in non-marital fertility have resulted from progressively increasing exposure to the higher fertility of consensual unions instead of to the very low fertility of single women. Cohabitational first-birth fertility is not high compared with marital fertility.