Slaapmiddelen en karaktertype

Before the war the Institute of Praeventive Medicine issued an inquiry about the personal use of narcotics by physicians, part of it regarding the influence of the character. The scheme of Heymans and Wiersma being considered most apt to render characterising numbers, questions were included to diagnose whether "activity", "emotionality" and/or "secondary function" are present. Statistical analysis of the returns from 1593 physicians, shows that emotionality highly enlarges the use of narcotics (not only by the fact that it is combined with more disturbances in sleep). Activity showed no influence, whereas it is possible that secondary function stimulates the use in a small degree. The different types of character act by their different amount of these three qualities only.     

Produktiviteit en statistiek

Productivity and Statistics.
Introduction to this special issue concerning productivity and statistics. Theauthor gives a brief general survey.     

Kans en behendigheid

"Skill and chance" .
According to Dutch law games of chance are forbidden. This leads to the exploitation of all kinds of mechanical plays where skill plays a part, but chance too. Opinions differ about the interpretation of the law, which does not give a clear definition of the kind of plays it wants to forbid. It is not even quite clear whether the distinction between games of chance and games of skill is relevant. In this paper, which is a reaction to H amaker's paper about the same subject in this issue, the thesis is defended that the distinction is necessary if one does not want the law to imply too much or too little.
Rapport S 409 (SP 113) van de Afdeling Mathematische Statistiek van het Mathematisch Centrurn, Amsterdam.     

Signaalstroomdiagrammen en Markov-ketens

The transient behavior of a simple two-state discrete Markov process can be studied by means of matrix-multiplication and z-transformations.
For linear systems the output is equal to the convolution of the input and the impulse response of the system. By taking z-transforms the convolution can be avoided: the transform of the output is equal to the transform of the input multiplied by the transform of the impulse response of the system.
The signal flow graph method is the transformation of the matrix-method of solving a system of simultaneous equations in a topological method.
The simple two-state discrete Markov process can be represented by such a flow graph and it is shown how to simplify this flow graph step by step. Taking as input the unit-impulse at time zero, the output of this system at time n turns out to be the n-step transition-probability.
The results for the transmission in a network are mentioned (Mason and Zimmermann [8]). With these results it is possible to give at once the n-step transition probability of a system without first simplifying the flow graph.
Building on this result signal flow graphs can be used to determine the chance to be for the first time in a certain state, the average number of times a system is in a certain state and the chance to reach a certain state for the first time before another state of the system has been reached.
Finally the results are extended to continuous Markov processes.     

Wiskunde en besliskunde

Mijne Heren Curatoren en Leden van de Raad van Toezicht, Mijne Heren Professoren, Lectoren en Docenten, Dames en Heren Leden van de Wetenschappelijke Staf, Dames en Heren Studenten en voorts Gij alien, die door Uw aanwezigheid blijk geeft van Uw belangstelling,     

Investeren en onzekerheid

Summary Investment and uncertainty
After a few introductory remarks about the necessity of uniform definitions about plan horizon, returns, expenses, interest factor ett. for all investment alternatives and the necessity of an also uniform way of prediction, several models on investment analysis which are known from literature are briefly discussed. For simplicity there is only one decision variable (i.e. capacity); the variables influencing it are called exogeneous variables. These exogeneous variables may be deterministic and then one has to maximize the sum of the discounted cash flows from each project where different levels of investment into a project are supposed to exclude each other. The maximization may be subject to restrictions or not. If the exogeneous variables are stochastic one has to maximize the expected utility, mostly defined by the expected value and the variance of the discounted cash flows. The way to carry this out is simulation. Also portfolio analysis may be used, but there are some objections against this method, which are discussed.     

Volatilidad en los ingresos y en el mercado de trabajo de los jóvenes en Europa

Los autores ofrecen nuevos datos empíricos sobre la volatilidad en los ingresos y en el mercado de trabajo (incluyendo entradas y salidas del empleo) de los jóvenes en Europa durante la Gran Recesión. Los datos de EU‐SILC para el periodo 2004–2013 revelan grandes disparidades al respecto entre los países europeos. La Gran Recesión incrementó la volatilidad entre los jóvenes. Mediante un ejercicio de descomposición de la varianza se observa una mayor rotación laboral en el sur de Europa. Según un modelo de efectos fijos, un mayor nivel de prestaciones de desempleo y de protección del empleo se asocia con una reducción de la volatilidad.     

Tijdreeksen en regionale jaarrekeningen

Since some acquaintance with the development of economic aggregates with regard to the town of Amsterdam is needed, the Municipal Bureau of Statistics calculated some of these quantities during the period 1953–1960. The data derived from the Social Accounts 1953 of the city of Amsterdam were taken as a starting point for the calculations. The present article has been Written to show the principles of construction.     

Medición de la vulnerabilidad en el empleo en Europa

El aumento de los contratos atípicos y de la rotación laboral en Europa está intensificando la vulnerabilidad en el empleo. Con datos de la Encuesta Social Europea de 2008 y mediante análisis de correspondencias múltiples, los autores elaboran tres índices de vulnerabilidad en el empleo (en función del empleador, del puesto de trabajo y de ambos), que aplican a una muestra de 29 países, fundamentalmente europeos. El primero (equivalente a la definición de empleo vulnerable de la OIT, basada en países en desarrollo) explica el 51 por ciento de los datos. En el segundo, resultan determinantes la categoría ocupacional y la ausencia de responsabilidades de supervisión.     

De Wet en de kansspelen

In the Netherlands all gambling is forbidden except in a few cases specially mentioned in the law. Time and again specialists in probability theory or statistics are called upon to testify as experts in lawsuits against law evaders. This paper discusses the part played by the experts in such legal procedures. It is pointed out that according to Dutch jurisprudence there does not exist an exclusive distinction between games of chance and games of skill. A simple declaration by an expert that a given game is largely based on chance suffices to see the game sentenced as against the law. This and various other related questions are discussed in detail and illustrated by examples taken from personal experience in the courts.     

Gemiddelde en kwadraatsom opnieuw bekeken

In 1952 merkte V an Y zeren [1] in dit tijdschrift op dat in de meeste elementaire leer-boeken de onafhankelijkheid van en s ², berekend uit een aselecte steekproef uit de normale verdeling, niet wordt bewezen.
In net bulletin van de VVS 1975, nr. 8 wijdt ook D e K roon [2] hieraan aandacht.
Om de in laatstgenoemd artikel ontwikkelde gedachtengang nog eens onder de aandacht te brengen met name ook van statistische assistenten en analisten en hun docenten, wordt in deze mededeling de hierna te formuleren stelling tot in details elementair bewezen.     

Diferencias regionales de las primas por calificación en la China urbana. Repercusiones en el crecimiento y en la igualdad

A partir de datos de encuestas de hogares, los autores observan que las primas por calificación aumentaron en toda China entre 1995 y 2002, pero solo en las provincias costeras entre 2002 y 2007, año en que estas también registraron mayor desigualdad salarial y contribuyeron más a la desigualdad salarial urbana total. Según un modelo de efectos fijos estimado, la privatización explica la evolución del primer periodo, y la integración de China en la economía mundial, la del segundo. Reducir la desigualdad exige, según los autores, la reforma del Registro de Población Hukou, que obstaculiza la movilidad de los trabajadores calificados y posiblemente también el crecimiento.     

Winstgevendheid en winstkansen bij valuta-arbitrage

Profits and Profit Probabilities in Exchange Arbitrage.
For the case in which in each of a number of countries buying and selling prices for the currencies of the other countries are quoted by a number of banks, a method is developed by means of which the chains of transactions which yield the highest profit, if any, are traced systematically. This method is applied to constellations of buying and selling prices in five countries at three different points of time; the maximum proft of chains was0.090, 0.477 and 0.143 per thousand, respectively.
When it is assumed that the logarithms of changes of buying and selling prices are normally distributed around o with constant variance and temporally independent, the probability that there is a positive profit can be determined for each chain at each point of time as soon as an estimate of the variance is available. In the same way the mathematical expectation of profit, when possible losses are considered as o (no action being taken), can be determined. Both quantities are calculated for two points of time for a limited number of chains.     

Het opinieonderzoek en de verkiezingen

The comment on the public opinion poll concerning the results of the election 1946 is discussed. It is shown that the mean error, being dependent on the number of parties, cannot be used to express numerically the goodness of the forecast.     

Gasto en seguridad social y rendimiento empresarial. El caso de las pymes en Indonesia

A pesar de la amplia bibliografía sobre la relación entre cotización social y rendimiento empresarial, la evidencia relativa a las pymes de las economías en desarrollo es escasa. Se examina aquí el caso de Indonesia utilizando datos censales empresariales de 2010 a 2014. Un aumento del gasto en seguridad social del 10 por ciento se asocia a un aumento del ingreso empresarial por trabajador de hasta el 2 por ciento. Los beneficios no disminuyen con el aumento del gasto en protección social, lo que sugiere que la ampliación de las prestaciones sociales puede ser una inversión empresarial que vale la pena.