bluuebunny/crossref_metadata_2025_split huggingface dataset:
Is diptherie een vermijdbare ziekte?‘*
Authors: Hoogendoorn D. 
Published: April 2008

SummaryIs diphtheria avoidable?Inoculation against diphtheria has in the past been practiced with different intensity in different parts of the country; but a direct comparison of percentages of the population falling ill does not provide any trustworthy information as to the effect of inoculation, because an epidemic does not reach its peak everywhere i the same year, and because marked differences in morbidity are known to exist between dgferent groups of the population quite apart from the effect of inoculation.It was observed, however, that inoculation was mainly applied to persons between 5 and 14 years of age, and this fact has been used as a basis for investigating its efficiency. To this end two indices were employed, viz:I1=number of cases in the group below 5 years/number of cases in the group above 14 years andI2number of cases in the group from 5 to 14 years/number of cases in the groups below 5 and above 14 yearsThese were computed separately for different boroughs; I1 over a period of about 20 years from I924 onwards, and I2, over the two epidemic years I942 and 1943. The data mentioned in this article refer to 1943 only.The index I1 is largely independent of inoculation, because few persons in both the age groups considered were inoculated. Hence I1 enables us to investigate what social factors influence the distribution of diphtheria cases amongst dgferent age groups. It was found that density of population and family size were the two main influencing factors, which between them could explain by far the greatest part of the variation in I1 (multiple correlation coefficient of 0.94).The index I2 depends on inoculation, because inoculation is mainly practiced on the group occurring in the numerator. Hence by comparing the index I2 for boroughs where the degree of inoculation was ‘good’, ‘medium’, and ‘bad’, we obtain information concerning the effect of inoculation. The results obtained with I1 made it possible, however, to group the boroughs in such a manner that the disturbing effect of population density and family size could be in a large measure eliminated, so that the effect of inoculation could be estimated with much greater certainty.This effect turned out to be highly significant.It is estimated that by regular inoculation the risk of falling ill with diphtheria can be reduced by about 61%, and the risk of death by 78%, while various arguments suggest that these estimates must be too low, and that the real effect of inoculation is higher still. Whether it will be possible by systematic inoculation of the whole population altogether to eliminate diphtheria cannot positiuely be decided, but can not be excluded either.
Het gebruik van bewegende gemiddelden voor de analyse van een economische grafiek
Authors: Storch J. M. 
Published: April 2008

SummaryPart A of this paper is devoted to U discussion of the properties of linear operators, briefly called ‘linors’. To the well known series of operatorsΔ= (1,‐2,1), Δ4= (1,‐4,6‐4,1) etc, a series S2= (1,2,1), S4= (1,4,6,4,1) etc. is made to correspond. The series Δ2k is shown to have a detrimental influence on the trend in a time series, whereas the series S2k will retain the trend but remove random errors and cyclical variations. By combination of Δ‐ and S‐linors a linor is derived which may reasonably be assumed to retain the trend and the cyclical variations but to remove the random errors.Next a simple type of moving average operator is deduced which is adopted as giving the trend alone. By a systematic application of these linors a time series can be split up into a trend, a cyclical vuriation, and a random rest.In part B this analysis is performed with two different economic time‐series, while in part C some general considerutions concerning the degree of regression, the reduction of errors, and the smoothness and fitting of linear operators are developed.
Twee frequentieverdelingen op het terrein van het voedingsonderzoek*
Authors: Fortuin G. J. 
Published: April 2008

SummaryTwo frequency distributions concerning the consumption of food.By interviewing, the caloric amount of food consumed by 294 different persons during a single day was determined and compared with the amount estimated from weight, length, age and sex according to standard practices. The quantityR = 100 log Calories observed/Calories estimatedhas a distribution shown in fig. 1. The variance is fairly large.In another experiment the caloric food consumption was determined for 22 different persons each day during a fortnight and the quantities.x' = 100 log Observed caloric consumption per day/Average caloric consumption per daywere computed and plotted in a histogram (fig. 2). The varaiance of x' is found to be considerably less (± 30) than the variance of R (122) from which it is concluded that errors inherent in the surveying technique were probably not the major cause of the high variance of R.
Gebruik en toepassing van waarschijnlijkheidspapier*
Authors: Exalto L. J. H. 
Published: April 2008

SummaryThe use and the application of probability paper.The technique of plotting a frequency distribution as a cumulative distribution on probability paper, and of determining the average and the standard deviation in a simple way from such a plot, is described. It is emphasized that when we use this technique the choice of the size of the classes is relatively of little importance. Besides, the plot on probability paper renders it possible to evaluate in simplefashion the influence of changes in the mean or in the standard deviation on the percentage of observations falling above or below a given limit. The paper is concluded by a discussion of some examples in which the plot canaot be approximated by a straight line, and of the way in wich diflerent types of deviations may be explained.
Het belong van automatische monsterneming; mogelijkheden en toepas‐singen*
Authors: Visman J. 
Published: April 2008

SummaryAutomatic sampling; its possibilities and applications.The problem considered is that of sampling a lot of coal or ore in order to determine the average content of some essential component; as a particular example the sampling of coal for ash content is taken.Three sources of error are considered, namely:

the sampling error, depending on the size of, and the distribution of ash content amongst, the grains; this error can be reduced by taking a large sample;
the error due to inhomogeneities in the lot, which can be cut down by using a gross sample composed of a large number of increments; and
the error in the analysis, including the errors introduced by grinding and dividing the gross sample into the final sample of about 1 gram used for the determination of ash content.

The accuracy (a) corresponding to 99% confidence limits is expressed in a simple formula, (1), in which the influence of each of the sources of error is represented by a separate term. Taking as a lot the coal produced at a mine during a shift, the formula shows that, to achieve a reasonable accuracy of a =i/0 ash, at least some 150 to 200 increments have to be taken, the second sourse of error (inhomogeneity of the lot) being by far the most important one. The size of the increments can be relatively small so that the weight of the gross sample stays within acceptable limits.This large number of increments necessitates the use of an automatic sampling procedure. In § 3 a sampler developed and installed at one of the Dutch State Mines is described together with the precautions required to prevent bias in the samples due tj segregation of the coal across the conveyor belt.For further details the English reader may be referred to Fuel 19, 101–105,1950.
lets over inkomenselasticiteiten, afgeleid uit huishoudrekeningen van gezinnen
Authors: Stuvel G. 
Published: April 2008

SummaryOn income elasticities derived from family budgetsThis is a small part of a research into income elasticities, which was started when dr Stuvel was working under Prof. Richard Stone at the Department of Applied Economics of the University of Cambridge and was continued after dr Stuvel's return to Holland.Advantages and disadvantages are discussed of the two alternative methods of calculating income elasticities, to wit from time‐series or from family budgets. The first method is appropriate if one is interested in short‐term changes in consumption by changes in income; the second method is suitable whenever the economist's interest is centred on long‐term changes in consumption. The mathematical form chosen for the regression equations on family income is: C = aYb so that the income elasticity is independent of income.
Het gebruik van correlatierekening, om de homogeniteit van een reeks waarnemingen te controleren
Authors: Drion E. F. 
Published: April 2008

SummaryTesting homogeneity of a series of observations by correlation analysisFour methods of preserving food were compared by having ten tasters independently judge appearance, flavour, consistency and taste of each of four components of the menu. The tasters laid down their judgment in one of the figures o, 1, 2 or 3. For each taster the correlation coefficient was calculated between his 16 totals (4 components × 4 methods of preserving) and the average totals of the other tasters.Divergent results were found for taster no. 1, 4 and 10 (practically no correlation) and taster no. 2 (negative correlation). Taster no. 2 appeared to have used the scale wrongly. This could consequently be corrected. The results of taster no. 1, 4 and 10 were eliminated, which led to better results into the consecutively executed analysis of variance.
Betrekkingen tussen de regressiecoëfficiënten van Galton en Frisch bij lineaire transformatie
Authors: Levert C. 
Published: April 2008

SummaryRelations between the regressioncoëfficië nts of Galton and Frisch in case of lineair transformationRelations are derived between Galton's two regressioncoëfficiënts and Frisch' diagonal regressioncoëfficiënt. The last is proved to be the geometric mean of the other ones. The influence of several kinds of lineair transformation on correlation and regressioncoëfficiënts is discussed. The paper is followed by some exercises.
Toepassing van de bezettingstheorie op een coderingsvraagstuk
Authors: de Wolff P. 
Published: April 2008

SummaryAn application of the occupancy theory on a coding problemFor large scale registration of certain medical phenomena it is very useful to have the disposal of a coding system which enables the reconstruction of the code number of a given person at any moment from the smallest possible number of personals. For this purpose, place and date of birth and sex may be used. These items, however, are not sufficient as they do not permit to distinguish between persons of the same sex, born at the same day in the same place. For Amsterdam this number is about 20. Therefore the Inspector of Public Health considered the possibility of including the birthday of the mother in the data and requested the Municipal Bureau of Statistics of Amsterdam to estimate the percentage of duplications which would occur when this enlarged system of personals were used. A special investigation for September 1951 turned out a rate of 10% which seemed to be rather high even if the number of twins for which duplications by their very nature would occur was taken into account. So it became interesting to know which rate theoretically might be expected.If we suppose the birthdays of the mothers of the persons born on the same day and in the same place to be evenly distributed over the days of the year, it is easy to calculate the expected number of duplications.We are then led to consider the following occupancy problem: n objects (number of births on a given day) are distributed over N places (possible birthdays of the mothers), the probability to occupy a certain place is the same for all objects and independent of the place. What is the probability that no places will be empty, n1 occupied by only one object, n2 by two objects etc.? It is shown that this probability is equal to From this formula the expectation and the variance of the number of persons with equal code numbers can easily be derived.The empirical results for 4 different months of 1951 (including the already mentioned month of September) proved to be in good agreement with these theoretical calculations.
Parametrische en parametervrije methoden en hun toepassingen*
Authors: Hemelrijk J. 
Published: April 2008

SummaryParametric and non‐parametric methods and their applicationsThe rapid development of non‐parametric methods in statistics raises the question of the difference between these methods and the classical parametric methods and of their different fields of application. This paper, read at a meeting of the “Vereniging voor Statistiek” on March 6, 1952, attempts to throw some light on this problem by means of two examples. A short exposition of an application of the method of moments of K. Pearson to the estimation of a population is given for a case, where this method is quite adequate and where it would be difficult to find an equally adequate parameterfree method. On the other hand a method of determination of histamine in human blood is described, which is based on an application of the method of m rankings of M. Friedman and M. G. Kendall. In this case the transition from the classical methods to parameterfree methods constitutes a real gain in rigour and efficiency.
Elemental r bewijs van de onafhankelijkheid van gemiddelde en spreiding bij steekproeven uit een normale verdeling
Authors: van IJzeren J. 
Published: April 2008

SummaryElementary proof of the independence of mean and variance of samples from a normal distribution.Usually the independence of mean and variance of samples from a normal distribution is proven by some n‐dimensional reasoning. The present article starts by proving the independence of the sample‐mean mn and the “deviation” xn–mn–1 of the last sampled element from the previous sample‐mean. This result gives an easy approach to the independence theorem, which is proven by a step‐by‐step process. A more elaborate version of the proof reveals the nature of the s‐distribution. Use is made of the n–i deviations xi–mi‐1(i = 2, 3, …, n), which are completely independent and represent the n–1 degrees of freedom in s.
Voorspellen in de toegepaste psychologie
Authors: de Groot A. D. 
Published: April 2008

SummaryPrediction in applied psychology.In applied psychology a distinction is needed between implicit and explicit prediction. Predictions, on the basis of test results, of educational or professional success belong to the latter category. The statistical techniques used are generally simple, since the different data are combined into a psychologically understandable structure rather than into a formula, this structure as a whole serving as basis for the prediction.Very often predictions are implied — or even hidden — in more or less conditional or intrinsic statements. This is partly a result of a tradition of caution. But this caution often interferes with the exigency that specific scientific statements be directly testable.As an example of (implicit) prediction of a chronological sequence the results of a research into the effects of war circumstances upon the intelligence level of schoolchildren were quoted. In 1946 a recovery to the normal pre‐war level, within 5 to 10 years, was correctly predicted.
Sequente analyse bij keuring van goederen
Authors: Storch J. M. 
Published: April 2008

SummarySequential samplingA simple survey of Walds theory of sequential sampling is given, followed by a modification of the rejection and acceptation lines. The rejection and acceptation lines of the Waldtest are lines of a constant ratio between the likelihoods of two hypotheses. The modified rejection and acceptation lines are curves, giving a constant ratio between the likelihood of one hypothesis and the maximum likelihood.The modified lines closely fit those of Wald, but ensure a natural end to the sampling before a given sample number is reached. A simple manner to evaluate rejection and acceptation probabilities of a hypothesis is still lacking, the computation now being quite inconvenient.
Een opmerking over het aanpassen van functies aan een groot aantal waarnemingsuitkomsten
Authors: Kuiper N. H. 
Published: April 2008

SummaryNote on the fitting of a function to a large number of observations.The paper deals with various ways in which a set of functions may be chosen to describe a given body of observations, the parameters determining the function being determined by the data.The special case when the functions of the set are given in the form of a table or a graph is emphasized.
De vervaardiging van een systeem functie‐ponskaarten
Authors: Erlee Th. J. D. , Koene A. A. 
Published: April 2008

SummaryWhile making a series of 10,000 “function” ‐punched cards with the data of the well‐known Barlow's tables and with the logarithms of the integers from the tables of Schrön, we took the opportunity to examine the accuracy with which our personnel and machines are working under normal conditions. We examined for instance in how many cases the first punching operator did not notice an error she made and how many of those errors remained after control‐punching. These last‐mentioned errors were traced by control‐calculations with the punched cards, e.g. by calculating and checking n × n2=n3 or by the calculation of differences. In this way it appeared that the first punching operator did not notice 270 errors in the part coming from Barlow's tables, being 0.055% of the number of punched columns or 2,7% of the number of cards. Further it was found, that only one error of the first operator was not noticed (or not corrected) by the controling operator.Besides this a number of printing‐errors, or anyway errors which were the result of the bad legibility of the digits, were found in Barlow's tables, where the punching operator and the controling operator had come to the same interpretation.The article gives in some detail what precautions were taken by wiring the machines to attain that an error would be noticed as such.
Een toets tegen verloop voor een aantal kansen *
Authors: van Eeden Constance 
Published: April 2008

SummaryA test against trend for a number of probabilities.This is an expository paper on a test for the equality of a number of probabilities against the alternative hypothesis of a trend, first described by Constance van Eeden and J. Hemelrijk [2]. In section 2 the test is illustrated by means of an example and methods are given to determine the exact distribution of the test statistic under the null‐hypothesis and an approximation for this distribution is described. Section 3 gives the general formulation of the test and section 4 contains a generalization. In section 5 methods are given for combining independent tests of this kind.
Tien jaar ontwikkeling van de maatschappelijke statistiek *
Authors: Idenburg Ph. J. 
Published: April 2008

SummaryA decade of social statistics.The development of descriptive statistics in the post‐liberation period can be characterized by the concepts integration and differentiation: side by side with an increasing knowledge of totality there is a constantly growing attention for detail.More so than formerly the central aim of international statistics is the obtaining of a statistical total picture in which on the one hand various statistics and on the other hand various countries can be shown. Moreover, differentiation can be distinguished: on the one hand as to fields of research, on the other hand as to geographical territories.Also from a national point of view there are intensive, integrating tendencies. There is e.g. the system of national accounts in which statistics perform an Emportant executive task.Improvement of information and statistical co‐ordination have been taken in hand; consistency is a requirement of the first order and regionalisation is often necessary.With respect to productivity — of major importance for the prosperity of our country — statistics were faced by a great task; much statistical work was done, productivity centres were established and research was organized.Furthermore random sampling technique and public opinion polls, which are indispensable to efficiently collecting statistical data, show an amazing development.More and more research and planning are making use of statistics.
Naar efficiënte experimenten
Authors: Hamaker Dr H. C. 
Published: April 2008

SummaryTowards efficient experiments. Under industrial conditions, where we encounter large random fluctuations, large numbers of observations, and a multiplicity of influencing factors, a proper analysis of the data on a statistical basis has become an essential part of our experimental techniques, which ultimately leads to more efficient methods of experimentation. This is illustrated by 7 practical examples. The first 4 examples deal with simple experiments for comparing two batches of raw materials when disturbing factors such as a time trend must be eliminated. The last 3 examples discuss more complex cases, namely a three‐factor experiment in the foundry, a latin square experiment in nylon spinning, and a five‐factor experiment of a mixed kind on gear‐noise testing.An attempt is made to explain in a simple form the relation between the statistical analysis of and the technical conclusions to be drawn from the result of a properly designed experiment.
Kwaliteitsnormen
Authors: Wijtenburg J. M. 
Published: April 2008

SummaryIn most cases the buyer of durable consumers' goods cannot judge of the essential consumption characteristics, and is consequently guided by the finish.The manufacturer should bear this in mind, and should pay much attention to the outward appearance of these articles.Quality control is difficult to realise here, since in most cases the relevant properties cannot be measured because of their most subjective character.By means of a case study (bath‐tubs) the author illustrates the measures which had to be taken to effectuate quality control, and he mentions the results and successes yielded.
Operational Research — managers beslissen met behulp van de wetenschap *
Authors: Sittig J. 
Published: April 2008

SummaryThis paper is an introduction to six short lectures about the theme “choice and chance”, implicated in different fields of human activity. It throws some light on the history, the methods and the importance of Operations Research. Attention is paid to the elements of the way which leads from putting the problem to taking the decision. A general illustration is given by means of a simplified example. Some remarks are made about post‐war development, task and future of O.R.
Het probleem van de ruïnering der spelers
Authors: Meinesz M. 
Published: April 2008

SummaryThe gambler's ruin.When a single trial has two possible outcomes A and B, with probabilities p and q(p+q= 1), a succession of these trials forms a so‐called Bernoulli chain. The well‐known result for the probability of n times A and m times B isIn this article we consider the ruin problem, in which the initial capitals of the gamblers are a and b, respectively. In stead of a Bernoulli chain we then have a Markoff chain, with coefficients that are less simple than the ordinary binomial coefficients.A more general expression (formula 1) is obtained for the probability distribution of the gambler's profit after a certain number of games, provided none of them became ruined beforehand. The probability for ruin after a certain number of games is a special case, similar to the results of Lagrange, Laplace and others, but appears in a form, more suitable for numerical calculations.Some other results, obtained through the same method as developed in this paper are indicated.