bluuebunny/crossref_metadata_2025 huggingface dataset:
The influence of skin tone, hair length, and hair colour on ratings of women's physical attractiveness, health and fertility
Authors: SWAMI VIREN , FURNHAM ADRIAN , JOSHI KIRAN
Published: April 2008

The present study investigated the role of skin tone, hair colour and hair length in perceptions of women's physical attractiveness, health and fertility. One‐hundred and thirty men and 112 women rated a series of 12 line drawings that varied in three levels of skin tone, two levels of hair colour and two levels of hair length. Results showed a number of interactions between the three variables, suggesting that these phenotypes are highly intercorrelated. However, there were also significant main effects of each of the variables, with hair colour generally explaining the greatest amount of variance. In general, light‐toned figures were rated the most positively. Contrary to expectations, however, brunettes were rated more positively than blondes, and hair length had only a weak effect on ratings of attractiveness. Implications of these findings and the limitations of the use of line drawings are discussed in conclusion.
Measurement invariance of personality traits from a five‐factor model perspective: multi‐group confirmatory factor analyses of the HP5 inventory
Authors: GUSTAVSSON J. PETTER , ERIKSSON ANNA‐KARIN , HILDING AGNETA , GUNNARSSON MATTIAS , ÖSTENSSON CLAES‐GÖRAN
Published: April 2008

Associations between personality and health may be influenced by contextual factors varying across studied cohorts. Moreover, measurement bias related to contextual factors could also influence these associations. Gender and age have been discussed as important contextual factors when studying personality and health outcomes. An examination of measurement invariance across gender and age may therefore be warranted. In the present study, measurement invariance across age and gender was examined for a five‐factor model of personality traits in which scales have been included to operationalise lower‐order traits related to health‐behaviour or health outcomes. Using multi‐group confirmatory factor analysis on a population based cohort (n= 5700), all important parameters of the measurement model were found to be invariant. On the basis of this invariant model, hypotheses of mean differences across age and gender in personality traits were tested. These results were discussed in relation to meta‐analyses on personality change and gender differences in personality.
Het opinieonderzoek en de verkiezingen
Authors: Vorangot W.
Published: April 2008

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.
STATISTICA: De Overschrijdingskans
Authors: Bok S. T.
Published: April 2008

If we want to check a hypothesis by numbers, obtained from measuring or from counting in a random sample, practically always a difference will be found between these numbers and those, derived from that hypothesis‐Such a difference may be caused by faults in the hypothesis or by factors which we do not want to analyse such as faults in the measuring or the influence of the sampling or influences acting together with the one regarded in our hypothesis.

The theory of statistics shows a way to estimate the chance that such another cause would result into a difference equal to or large than the one actually found. If in a given case this “chance of surpassing” is found to be small, we have to reject the hypothesis concerned. The smaller this chance is the larger is the likelihood of that rejection; it is the estimate of the likelihood of each statistical conclusion.
Enkale statiatische atpecten van het opinie‐onderzoek
Authors: Varangot V.
Published: April 2008

The discussion of the results of the public opinion poll (May 1946) is continued. The forecasts are judged by the χ2 sum.

The correspondence of forecasts and results cannot be measured by the coefficient of correlation.
Statistische hulpmiddelen bij de. kwaliteitsbaheersing II1
Authors: Enters J. H.
Published: April 2008

An exposition is given of the methods of statistical quality control of a flow of products from a particular production process in cases where quality is being measured by the number of defectives in a sample. Examples are given of the way in which this is being done in cases where go — not go gauges can be applied.
Eenige statistische opmerkingen over verpakkingsen doseeringsproblemen
Authors: Sittig J.
Published: April 2008

In packing powders, fluids and the like in mass production there are three frequency distributions of weights, viz. net weights, gross weights and tare weights. It is shown that by elementary statistical methods the standard deviation of one of these three distributions may be found by analysing the other two.

The excisting correlation, e.g. between net weights and tare weights, can be found by the same methods.
Typologie van den statisticus Hoe men hem ziet en hoe hij
Authors: van der Burg Drs A. R.
Published: April 2008

In the popular conception the statistician is a man who collects and groups figures which he publishes in the form of tables and graphs. The real statistician in the modern sense of the word, i.e. the man who does not collect the material but analyses it and draws his conclusions from it, is as yet practically unknown to the general public. It is desirable that more publicity should be given to the characteristic qualities required for this calling, so that those most fitted for i may be drawn towards it.

The aspiring statistician should be taught to think in statistical terms and not along functional or determinist lines, as the mathematician does. The statistician is only interested in individual phenomena insofar as they enable him to draw conclusions of a more general character out of a certain amount of isolated cases. A true sense of proportion is very important as it plays a major part in the framing, the working out and the conclusions to be drawn from the solution of the problems. As the sphere of his activities is so extensive, the statistician should be able to adapt himself quickly to new situations.

Those who are endowed with these varying talents can rely on finding a very useful task as a statistician.
Drie soorten statistiek in de natuurkunde?
Authors: Schwarz N.
Published: April 2008

Summary  (Three kinds of statistics in physics).

A simplified derivation is given of the energy‐distribution of Maxwell‐Boltzmann, Bose‐Einstein and Fermi‐Dirac. The importance and the application of these laws are considered, and the fundamental hypotheses, on which they are based are mentioned.

It is shown that only one sort of statistics is used, but that the statistical method is adapted in each case to the special physical properties of the particles, to which this method is applied.
Blanco proeven
Authors: Post J. J.
Published: April 2008

Summary  (Uniformity trials)

Uniformity trials can give information about the variation between individual observations. The number of blocks in the following trial, necessary to decide upon the significance between the main effects, can be derived from the value of the coefficient of variation (b.sigmax, %).
De kosten van levensonderhoud te ‘s‐Gravenhage in December 1946
Authors: Vermeulen A. J. M.
Published: April 2008

Summary  (The minimum costs of living at The Hague in December 1946).

Standards are given for the minimum costs of living in December 1946 for families of different composition and different gross wages.

Fig. 1 shows the family income as a percentage of the necessary expenses.

In Fig. 2 a specification is given of the total expenses for families with respectively 0, 2 and 4 children and for single persons not living with their families.

The expenses are divided into: A. taxes and insurance, B. costs of food, C. costs of housing, D. repairs of clothes etc., E. procuring of new clothes and household utilities.

Samenvatting

In onderstaand overzichtje geven wij nu voor ieder gezinstype het inkomen, excl. kinderbijslag, dat nodig is a. om de minimaal noodzakelijke kosten te kunnen dekken en b. om bovendien ook de boven beschreven niet‐minimaal noodzakelijke uitgaven te kunnen doen.

Wanneer we de niet‐minimaal noodzakelijke kosten buiten beschouwing laten en alleen de dekkingspercentages bezien, zoals dezr uit fig. 1 af te laten zijn, dan zien we, dat ondanks de onlangs verhoogde kinderbijslag ook thans nog vele gezinnen niet in staat zijn om aan hun meest dringende verplichtingen te voldoen.

Dat dit aanleiding geeft tot zeer ongewenste toestanden zal iedereen duidelijk zijn. In vele gezinnen toch zullen bonnen, welke niet gerealiseerd kunnen worden, te gelde gemaakt worden. Dit geldt in het bijzonder voor snoepbonnen, extra bonnen voor kinderen (zoals voor sinaasappelen en eieren) enz.

Dit rapport wil niet de pretentie hebben aanwijzingen te geven hoe hierin verandering gebracht kan worden. Wij stelden ons slechts ten doel door het publiceren van concrete gegevens de aandacht te vestigen op de financiele nood, waarin duizenden zich bevinden ten gevolge van de wanverhouding tussen lonen en prijzen.

Daarnaast meenden wij goed te doen door richtlijnen te geven voor de besteding van het inkomen, in het bijzonder voor zover dit betreft de posten voeding en nieuwe aanschaf.

Men dient echter steeds voor ogen te houden, dat deze richtlijnen zéér ruim genomen moeten worden. Er zullen vele factoren zijn, die een afwijking van de gegeven verdeling nodig of gewenst zullen maken. Zo zal het bij de uitgaven voor nieuwe aanschaf van belang zijn of men al dan niet oorlogsslachtoffer is.

Voorts zal men ook rekening dienen te houden met een verhoging van de post voeding bij toekenning van extra‐rantsoenen voor langdurige, zware of zeer zware arbeid.

Ten slotte verdient het vermelding, dat behalve van de in het literatuur‐overzicht genoemde publicaties, speciaal voor de post voeding gebruik werd gemaakt van gegevens van het Voorlichtingsbureau van de Voedingsraad te s‐Gravenhage.
Weersverwachting op lange termijn
Authors: Visser Prof. Dr S. W.
Published: April 2008

Summary  (Long range weather forecasts. II The correlation ellipses).

The description of the method for determination of long range weather conditions, as presented by the Kon. Ned. Meteorologisch Instituut at De Bilt, is continued.

The formulae lead to the construction of socalled correlation ellipses which are of great use to find the best new variables to be added in order to improve correlation. The calculus is very simplified by this method, which deals with the complicated correlation phenomena; reliable results can only be obtained by careful application.
Naschrift bij het artikel van Mr W. H. Somermeijer
Authors: Enters J. H.
Published: April 2008

Summary  (Post scriptum by Mr. Enters).

Spearman s saturation coefficient which is computed from correlation coefficients between series of measurements by several inspectors may be used to express the capacity of these inspectors for massinspection only if a systematic bias in their results may assumed to be not existing or is accounted for. As an example it is shown that the differences between the means of the measurements by the inspectors mentioned in the previous article (Statistica I, pag. 40) are not significant.
De bepaling van de nauwkeurigheid, waarmede metingen of beoor‐delingen worden verricht.
Authors: Posthumus Dr Ir G.
Published: April 2008

Summary  (Discussion of the accuracy of measurements and judgments).

In this paper a Summary is given of the methods, which are used or can be used to determine the accuracy, with which measurements, which can be expressed in concrete units (lengths, weights, percentages etc.), can be made.

An account is also given of a method, which can be used, when expression in concrete units is not possible (e.g. grading the odor or taste of butter or wine, judging the achievements of pupils by means of test‐work).
De functie van de econometrie bij het bedrijfsbeheer1
Authors: Dalmulder J. J. J.
Published: April 2008

Summary  (The function of econometrics in industrial and commercial management)

A mere theoretical discussion about the nature of econometrics and an analysis of the application in industrial and commercial management, specially from a statistical point of view.
Een systematische vergelijking van de statistische eigenschappen van hedendaagse steekproef‐schema's1
Authors: Hamaker H. C.
Published: April 2008

Summary  (A systematic comparison of the statistical properties of present‐day sampling schemes).

A survey of various sampling schemes, carried out with the aid of the, random walk diagram, ‘leads to the conception that it must be possible to effect the same degree of inspection by the application of different schemes. The degree of inspection of a scheme is contained in its, operating characteristic’, which is specified by two constants viz:

its centre q0, for which P = 1/2, and its slope s in this point, defined by

s= ‐(dP/dq)q=q0.

It is shown that, if the operating characteristics of two different sampling schemes possess the same values of q0 and s, the two characteristics are almost completely coincident. Thus two sampling schemes having the same q0 and s will give identical inspection performances, and are consequently defined as, equivalent. ‘And by comparing the average sample sizes of equivalent schemes we may compute their relative efficiency’. For each set of values q0 and s it is possible to construct a single sampling scheme possessing these characteristics. Hence to any scheme whatever there will correspond an, equivalent single sampling scheme, and, by adopting the single sampling scheme as a standard of reference, we may arrive at a general definition of efficiency.

By the introduction of q0 and s the formulae relating to the sequential sampling scheme are greatly simplified, and for each set of values q0 and s there is one corresponding sequential scheme.

By discussing a particular example of the double sampling scheme it is shown that the methods developed in this paper can successfully be applied to a systematic treatment of the variety of schemes now in existence.
Hyperbolische foutenwet
Authors: Brethouwer D. H. G.
Published: April 2008

Summary  (The hyperbolic law of errors).

In the first chapter some general questions concerning the error distribution are discussed and the deduction of the hyperbolic error distribution is given.

Next the properties of this distribution are shown and some fundamental data (standard deviation etc.) are determined.

Finally the hyperbolic error distribution is compared with the Gaussian distribution and tested in practice.
Toevals‐frequenties, een hulpmiddel bij de constructie yan kunstmatige steekproeven van grote omvang
Authors: Hamaker H. C.
Published: April 2008

The construction of large‐size random samples by means of random sampling numbers in the usual way requires much tedious labour. This paper describes a short‐cut technique by which artificial samples, of say 500 or 1000, can be obtained in about one tenth of the time. Use is made of previous records of the frequencies of two‐digit random sampling numbers; these are called the random sampling frequencies'.
Statistisch onderzoek van contrôle‐analyse cijfers: (De verdeling van het droge stofgehalte van het brood tijdens de tweede wereldoorlog)
Authors: Hekker Ir Th. , Straub Ir J.
Published: April 2008

Summary  (Statistical investigation of the distribution of data for the solids of bread (in loaves analysed in the Food Inspection Laboratory in Amsterdam))

The distributions of the data of the solids of bread as analysed during the years of the war are investigated. The means and the standard deviations are calculated, also χ2, kurtosis and skewness supposing the distributions to be normal. An example of calculation is given in table I. Actual numbers for different years are given in table II and in table III. The distributions were tested on normality because former investigations showed that the distribution of under survey prepared loaves did not deviate significantly from the normal.

It is found that generally the investigated distributions cannot be regarded as normal. Though symmetric they show leptokurtosis and the χ2‐test for the goodness of fit of normal equation gives values of P 0,01 (or a little more). Similar distributions were found by Clancey1) in his investigation of numbers of chemical analyses of industrial products (about 10% of the distributions showed this shape, some 10% were truncated leptokurtic curves) and by us for the fat percentage of meals from the governmental eating‐houses. The distributions are represented on probability‐paper. This way of representing results gives a clear view of the variations of the mean and the standarddeviation in the course of the years (fig. 1). The deviations of the shape of the normal straight line on probability paper by special causes is investigated (fig. 3, fig. 4, fig. 5, fig. 6 to be compared with fig. 2). With this “spectrum” of possibilities of deviations from the normal distribution in mind the special cause for the leptokurtic shape in our special case has been discussed.
Superpositie van twee frequentieverdelingen
Authors: Sittig J.
Published: April 2008

Summary  (Superposition of two frequency distributions)

Notation:

n: number of observations

M: arithmetic mean

s̀: standard deviation

μr: rth moment coefficient

β1: coefficient of skewness

β2: coefficient of kurtosis.

The suffixes a and b apply to the component distributions. The suffix t applies to the resulting distributions.

The problem: Given the first r moments of two frequency distributions (to begin with μ0). Find the first r moments of the distribution resulting from superposition of the two components (r≥5).

Formulae [1]. … [5] (§3) give the results in their most general form up to μ4.

Some special cases are treated in § 4, and eight different cases of superposition of two normal distributions in § 5.

In § 6 some remarks are made about the reverse situation, i.e. the splitting into two normal components of a combined frequency distribution.
De bewerking van de resultaten van veldproeven door herleiding van de opbrengstcijfers in beide richtingen van het proefveld
Authors: Stoffels Ir A.
Published: April 2008

Summary  (The treatment of the results of field experiments by reducing the yields in two directions)

Ir J. J. Dijkveld Stol has shown that good results have been obtained by reducing the yields of field experiments both in columns and in rows.

The mathematical foundation of this method is discussed in the preceding article and it is shown, that the method gives good results if the same supposition may be made as necessary for the application of the methods of Fisher, Knut Vik and the method of the differences.

The variance s̀ of Dijkveld Stol's method is identical with Fisher's error variance.
De ruis in radiobuizen ais statistisch verschijnsel*
Authors: Hamoker H. C.
Published: April 2008

Noise in radio valves as a statistical phenomenon.

If an electric current is interpreted as. the passage of a certain number of electrons per second, it is evident that such a current will be subject to statistical fluctuations. These fluctuations, commonly designated as “noise”, limit the maximum amplification applicable in radio reception. Some of the fundamental principles of noise formation are treated in this article from a statistical point of view. The formation of noise, noise suppression by space charge, current‐distribution noise, and noise due to secondary emission are successively discussed.
Anthropologische opmerkingen over anthropo‐sociologische feiten *
Authors: de Froe A.
Published: April 2008

Anthropological notes on anthropo‐sociological data.

Frequency distributions and correlations observed by van Ettinger and Sittig 1) in their extensive research concerning the body measurements of Dutch women, are here discussed from an anthropological point of view. In particular it is pointed out that a certain parallelism can be traced between the correlations of certain classes of measurements of the human skull and the correlations of analogous classes of measurements taken on the human body.
Een verband tussen zonnevlekken en extreme winters
Authors: Visser S. W.
Published: April 2008

A relation between solar activity and extreme winters

The well‐known II‐years period in solar activity is eliminated by computing moving averages of relative sunspot numbers over II‐year intervals. The averages thus obtained reveal a ‘long period’ probably of about 89 years. By subtracting the averages from the original figures reduced sunspot numbers are obtained which represent the normal II‐years fluctuations after elimination of the long period.

Standard deviations of winter temperatures have been computed in a similar fashion for moving II‐year intervals, and these standard deviations have been plotted against the average sunspot numbers in figs. 1 and 2, crosses referring to the years before 1831 and dots to the years after. Both at De Bilt and at Prague the observations from 1831 onwards exhibit a pronounced positive correlation, with correlation coefficients of +0.82 and +0.74 respectively. No such correlation can be detected in the earlier observations, which the author is, however, inclined to ascribe to the inaccuracy and incompleteness of the data collected in these early periods. As shown by fig. 3 no correlation does exist between the temperature deviations and the reduced sunspot numbers.

It must be concluded that extreme winters occur during the peak solar activities of the long solar period; the normal II‐years period is of no consequence.

From a statistical point of view these results are noteworthy: the standard deviation shows systematic variations which are doubtless of physical origin. Statisticians are advocated not to lose sight of the physical background when applying statistical methods to physical phenomena.
Het “Internationaal sfatisrisch Instituut” en het Congres te Bern van 5–10 Sept. 1949
Authors: Hamaker H. C.
Published: April 2008

The ‘International Statistical Institute’ and its session at Bern from 5 to 10 September.

A general survey Concerning the organisation and activities of the ‘International Statistical Institute’ and the papers contributed and discussed at its 26th session held at Bern from 5 to 10 September 1949.
Het aantal noodzakelijke waarnemingen bij toepassing van voortschrijdende steekproeven
Authors: Enters J. H.
Published: April 2008

The amount of inspection required in sequential sampling.

Sequential sampling plans as developed by Barnard
3)
are most easy to apply in industrial quality inspection if (in Barnard's notation) the ‘hand cap’ H and the ‘penalty’ b are so adjusted that Smin= H/n = a positive integer, n = b+1 being the size of the successive samples. Sequential sampling plans of this type for which Smin> 5 are not of great interest, because by their extreme severity they necessitate the inspection of too great a number of items. This paper presents the results of computations concerning the amount of inspection required by 4 Standard Sequential Sampling Plans, for which Smin= 2, 3, 4 and 5 respectively.

In table I the 0,05 producer's and consumer's risk points (pl and p2) of the operating characteristics of these sampling plans are given for n = 10, 15, 20, …. 100. It may be shown that the products np1and np2tend to a limit as n→∞.

When setting up a sequential inspection plan it is also necessary to be informed about the amount of inspection that will be involved. The average amount of inspection is a function of H, b, and p
i (the percetage of defectives in the batch). But even when H, b, and pi are constant the actual amount of inspection in a particular case may differ considerably from the average and may vary within a wide range; hence it is of importance to know its probability distribution.

Assuming a Poisson distribution for the number of defectives in a sample, the probability that a sequential sampling plan will necessitate a given amount of inspection will be a function of the product npi. For the four standard plans under consideration the 10, 20, 30, 40 and 50%points of these probability distributions are represented in figs 5–8. The sample sizes of single sampling plans possessing the same operating characteristics were found to be approximately 6n, 12n, 22n, and 35n respectively, and from figs 5–8 it will be seen that the actual amount of inspection in sequential sampling may considerably exceed the sample size of these equivalent single sampling plans, particularly in the region np1 < npi < np2.

As these extreme values may occasionally lay a heavy load on the inspection department it is desirable to curtail sequential sampling by setting an upper limit to the number of items that are to be examined. The effect on the operating characteristics of truncating the standard sequential plans after Smax samples of n items each have been drawn, is illustrated in figs 9–12. These show that if in the four cases under consideration Smax is fixed at 6, 12, 22 and 35 respectively, the amount of information lost by truncating is relatively small. The resultant truncated standard sequential plans can be condensed into very simple precepts which are easily learnt by heart by the quality inspector and have proved of great practical convenience.
Systematische en toevallige fouten bij het aflezen van de stand van een wijzer op een school *
Authors: Homaker H. C.
Published: April 2008

Systematic and random errors in reading the position of a pointer on a scale

In a prèvious article 1) V. Varangot has recorded the readings by 40 different persons of ten different positions of a pointer, the actual positions being known. He has pointed out certain discrepancies in determining according to different criteria who is the “best” estimator.

In the present paper Varangot's data are subjected to a further analysis. It is shown that the discrepancies are mainly the result of the existence of both systematic and random errors. If these are not clearly distinguished discrepancies as observed may always be expected. When, on the other hand, both types of error occur together it is very difficult, if not impossible, rigorously to decide who is the “best” estimator. Spearman's criterion based on correlation coefficients is shown to be unsatisfactory. Finally the order of magnitude of systematic and random errors in Varangot's data are deduced by a‘ regression analysis. A brief abstract of some further papers on this subject is given at the end.
Is diptherie een vermijdbare ziekte?‘*
Authors: Hoogendoorn D.
Published: April 2008

Is 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 and

I2number of cases in the group from 5 to 14 years/number of cases in the groups below 5 and above 14 years

These 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

Part A of this paper is devoted to U discussion of the properties of linear operators, briefly called ‘linors’. To the well known series of operators

Δ= (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

Two 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 quantity

R = 100 log Calories observed/Calories estimated

has 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 day

were 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

The 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

Automatic 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

On income elasticities derived from family budgets

This 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

Testing homogeneity of a series of observations by correlation analysis

Four 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

Relations between the regressioncoëfficië nts of Galton and Frisch in case of lineair transformation

Relations 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

An application of the occupancy theory on a coding problem

For 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

Parametric and non‐parametric methods and their applications

The 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

Elementary 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

Prediction 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

Sequential sampling

A 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

Note 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

While 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

A 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

A 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

Towards 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.