Note on sums of a random number of random variables with exponential family distributions

With the help of the result that exponential-type families are determined by their mean value functions it is shown that stochastic independence of the random variables S_N and N-S_N characterizes the Poisson and Bernoulli distributions simultaneously.     

An application of multiple objective linear programming to media selection

A multiple objective linear programming (MOLP) method utilizing interval criterion weights is applied to the problem of media selection. Using this technique, it is possible to analyze a problem more explicitly in terms of the several objectives inherent in many media selection situations. In order to illustrate the interval criterion weights approach, a multiple objective hierarchical media selection model is presented and its computer results discussed. In addition to being able to deal more directly with different decision criteria, a distinguishing feature of the mathematical analysis applied here is that its output enables the media-planner to be presented with a small cluster of candidate media schedules (rather than just one). Then, from this list, the media-planner should be in a position to qualitatively make a final choice as a close approximation to his optimal solution.     

Wertschöpfungspotenziale und strategische Implikationen einer Öffnung von Informationsressourcen – Phänomenologie und ein Bezugsrahmen

For some years, companies have successfully harnessed the value-creation potential of external resources by opening up their information resources, thus increasing considerably the value of their own resources. Corresponding phenomena, however, cannot be explained by common resource-based approaches. By providing a structure, our article contributes to a deeper understanding of this issue. We develop a framework, grounded in the Resource-Based View, that differentiates phenomena of opening up information resources between two dimensions: (1) access and (2) control. Our analysis motivates an extended view of information resources management that also accounts for enterprise-external resources. We conceptualize this view as the “management of information spheres,” highlighting the need for further research in the field of value creation related to external resources.     

On the optimality of the sample variance

The present paper explores the structure of linear exponential families for which the sample variance is a uniformly minimum variance unbiased estimator.     

On exact and optimal single-sampling plans by variables

We deal with sampling by variables with two-way protection in the case of a $N\>(\mu ,\sigma ^2)$ distributed characteristic with unknown $\sigma $ . The LR sampling plan proposed by Lieberman and Resnikoff (JASA 50: 457 ${-}$ 516, 1955) and the BSK sampling plan proposed by Bruhn-Suhr and Krumbholz (Stat. Papers 31: 195–207, 1990) are based on the UMVU and the plug-in estimator, respectively. For given $p_1$ (AQL), $p_2$ (RQL) and $\alpha ,\beta $ (type I and II errors) we present an algorithm allowing to determine the optimal LR and BSK plans having minimal sample size among all plans satisfying the corresponding two-point condition on the OC. An R (R: A language and environment for statistical computing, R Foundation for Statistical Computing, Vienna, Austria. ISBN 3-900051-07-0, URL http://www.R-project.org/ 2012) package, ExLiebeRes‘ (Krumbholz and Steuer ExLiebeRes: calculating exact LR- and BSK-plans, R-package version 0.9.9. http://exlieberes.r-forge.r-project.org 2012) implementing that algorithm is provided to the public.     

Price perception and confirmation bias in the context of a VAT increase

This paper examines a potential confirmation bias in price perception in consequence to a real-world event and different explanations for such a confirmation bias. In a panel design conducted 2 months before and after a raise in value-added tax (VAT), 303 participants had to estimate the current prices for four products affected and four products not affected by this raise in VAT and the anticipated or recalled prices of these products. Before the VAT increase, an undifferentiated belief in strong future price increases was prevalent. After the VAT increase, a confirmation bias was found: in retrospect, participants reported price increases that were significantly higher than the official price development and in line with an undifferentiated belief in marked price increases. Two theoretical explanations for confirmation bias, i.e., the biased use of price information and the selective distortion of memory, fit the data.     

The modularity of the ‘revolutionary’ repertoire of action in Egypt: origins and appropriation by different players

The Egyptian ‘revolutionary’ repertoire of action, that is to say the repertoire used by the protesters of January 2011, was characterized by a combination of several features: occupation of a symbolic place; ‘horizontal’ forms of organization; recourse to new electronic information and communication technologies (especially social networks); and rhetoric centered around universal values such as dignity, social justice, human rights, and democracy. This repertoire was born as a result of the merging of two parallel cycles of mobilization, which had actually started during the previous decade, one animated by activists from the educated middle class, and the other by workers struggling for economic and social reforms. After the fall of Hosni Mubarak in February 2011, it demonstrated its extreme modularity, being appropriated by different players from all sections of the political spectrum, from the Salafist hāzimūn to proponents of the military power.     

A hundred years of town planning and the influence of Ebenezer Howard

Book Reviewed:
Hall, Peter and Ward, Colin 1998 Sociable Cities: The Legacy of Ebenezer Howard     

Portfolio optimization: New capabilities and future methods

Summary  This paper addresses the problem of portfolio selection in finance. In many cases, currently available software to compute the efficient frontier runs into difficulty in problems with more than about 600 securities. To proceed beyond this size, it is often necessary to modify the problem in which case there is typically a loss of information. In this paper, we discuss a computer capability that can exactly compute mean-variance efficient frontiers of problems with up to 2,000 securities in very reasonable time (even if a problem’s covariance matrix is 100% dense). The paper also discusses an augmentation to the theory of portfolio selection that allows multiple objectives (such as dividends, liquidity, social responsibility, amount invested in R&D, and so forth) to be incorporated into the portfolio selection process. In such problems, the efficient set is no longer a “frontier,” but is now best described as a “surface” with the interesting property that it is composed of platelets (like on the back of a turtle). Moreover, the computer capability that can compute the exact efficient frontier of a mean-variance problem with up to 2,000 securities also has, after additional coding, the ability to compute exactly all platelets of the efficient surface of a tri-criterion portfolio problem with up to 400 securities.

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Zusammenfassung  In dieser Arbeit stellen wir einen leistungsf?higen Rechenalgorithmus vor, um den effizienten Rand (die nichtdominierten Alternativen) von Portfolio-Auswahlproblemen in der Finanzierung zu bestimmen. Wir bezeichnen den Berechnungsalgorithmus, der in Java programmiert ist, mit MPQ (multi-parametric quadratic programming). MPQ weist gegenüber bisherigen Berechnungsverfahren eine Reihe von Vorteilen auf: Es kann für umfangreiche Anwendungsf?lle genutzt werden, ist durch passable Rechenzeiten charakterisiert und kann die Menge effizienter Alternativen in einem Bruchteil bisher üblicher Rechenzeiten bestimmen.

     

Religiös-konfessionelle Kultur und individuelle Religiosität: Ein Vergleich zwischen West- und Ostdeutschland

In religious terms, East and West Germany are still two separate societies more than 20 years after reunification. While the large majority of the population in West Germany belongs to one of the two main Christian churches, the proportion of those without a denomination in East Germany is now more than 70 %. Moreover, as far as church involvement, confidence in the church and individual religiosity are concerned, the West Germans have a much stronger religious affiliation to the church than their East German counterparts. The main reason for this difference is the influence of different political systems and legal cultures in East and West during the period when the two parts of Germany were divided. The fact, though, that the process of secularization has continued unabated in East Germany since 1989, and that the religious and ecclesiastical discrepancies between the two parts of the country have, if anything, become stronger rather than weaker since then, would suggest that there are other factors at work here, too. In this contribution, we argue that one of the factors that needs to be considered is the dominant denominational culture that exists in each of the two parts of the country, a culture which is highly persistent, can easily reproduce itself, puts pressure on the respective minority cultures, and is able to diffuse into them. While the dominant denominational culture in West Germany is able to slow down the current processes of secularization, the secular, non-denominational majority culture in the East tends rather to produce effects which accelerate these processes. In this essay, we use a variety of empirical indicators (effectiveness of religious socialization, denominational affiliation, churchly affiliation, faith in God) to demonstrate these effects.