摘要:

Summary This paper is an exposition about the model and techniques in factor analysis, a method of studying the covariance matrix of several properties on the basis of a sample co‐variance matrix of independent observations onnindividuals. The indeterminacy of the basis of the so called factor space and several possibilities of interpretation are discussed. The scale invariant maximum likelihood estimation of the parameters of the assumed normal distribution which also provides a test on the dimension of the factor space is compared with the customary but unjustified attack of the estimation problem by means of component analysis or modifications of it. The prohibitive slowness of convergence of iterative procedures recommended till now can be removed by steepest ascent methods together with Aitken's acceleration method. An estimate of the original observations according to the model assumed, as to be compared with the data, is gi

ISSN:0039-0402    

DOI:10.1111/j.1467-9574.1968.tb01358.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Summary Let x1…, xnbe a sample from a distribution with infinite expectation, then forn→∞ the sample average x̄ntends to +∞ with probability 1 (see [4]).Sometimes x̄ncontains high jumps due to large observations. In this paper we consider samples from the “absolute Cauchy” distribution. In practice, on may consider the logarithm of the observations as a sample from a normal distribution. So we found in our simulation. After rejecting the log‐normality assumption, one will be tempted to regard the extreme observations as outliers. It is shown that the discarding of the outlying observations gives an underestimation of the expectation, variance and 99 percentile of the ac

ISSN:0039-0402    

DOI:10.1111/j.1467-9574.1968.tb01359.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Summary A branch and bound algorithm is given to solve the following problem: To each pair of elements (i,j) from a setX={l,…,n} a numberrijwithrij≥ 0,rij=rijandrij= 0 has been assigned. Find a prescribed number of disjoint subsetsP1…,PmfromX, such thatExperiments indicate that an optimal solution is usually found in a small number of iterations, but the verification may be rather time consuming.The algorithm may be used to find the minimum value ofmfor which a partitioning ofXwithz= 0 exists. The algorithm appears to be efficient for finding this ‘chromatic number of

ISSN:0039-0402    

DOI:10.1111/j.1467-9574.1968.tb01360.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Summary This is a study of the demand for the ownership of new or firsthand cars, i.e. the demand of ‘first owners’ who habitually buy new cars which are then traded in long before they are obsolescent. Upon combining the evidence of various surveys with time‐series for 1950‐64 it is found that this ownership has an income elasticity of 2 and a price elasticity of – 1.25 in respect of the constant‐quality index of new car prices earlier provided. On the average new cars are traded in after three years so that roughly one third of the existing stock is replaced every year. These values together determine an equation for purchases of new cars which accurately predicts new registrations in 1965 and 1966. Projections for the years 1967‐70 are provided.In the model employed the total number of cars (including used cars) is determined by the active demand exerted by ‘first owners’ on one hand and by the hitherto fairly constant scrappage rates on the other. Projections of the overall ownership rate can therefore be derived from the forecasts of new registrations. The ownership rate will approach 80% around 1970, and it is likely that at that stage the current scrappage rates will cease to apply in view of the greater predilection for compara

ISSN:0039-0402    

DOI:10.1111/j.1467-9574.1968.tb01361.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Summary In business practice it happens that annual growth is measured by the ordinary (arithmetic) average of yearly growth percentages. It is argued that there are better methods in any case. A method requiring relatively much time is least squares. Methods requiring very little time are a) determining growth graphically, using semi‐logarithmic graph paper b) computing the geometrical average, which is nothing else than then‐th root (if there aren+l observations) of the ratio between the last and first observation.In a table, a survey of bias and dispersion of three estimators is given for a few numerical

ISSN:0039-0402    

DOI:10.1111/j.1467-9574.1968.tb01362.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Book reviewed in this article:Statistiek voor S.P.D., H. J. A. v. D. POSTThe advanced theory of statistics (Vol. 3), M. G. KENDALL and A. STUARTHandbook of tables for probability and statistics, W. H. BEYERThe Theory of Probability, B. W. GNEDENKOElements of Nonparametric Statistics, GOTTFRIED E. NOETHERElementary Probability, EDWARD O. THORP, WileyThe Design and Analysis of Scientific Experiments, K. C. PENGScientific inventory management, JOSEPH BUCHAN and ERNEST KOENIGSBERGTime‐dependent Results in Storage Theory, N. V. PRABHUIntroduction to Operations Research, F. S. HILLIER and G. J. LIEBERMANProceedings IBM Scientific computing symposium; Simulation Models and Gaming, IBM Data Processing DivisionSpatial dispersion of economic activity, H. C. BosMonopolistic Competition, technical progress and income distribution, J. G. M. HILHORSTStatistical Techniques in Business and Economics, R. D. MASON, R. D. IrwinDe Genormaliseerde Methode van Werkclassiflcatie als Meetinstrument, A. HAZEWINKEL, J. B. Wolte

ISSN:0039-0402    

DOI:10.1111/j.1467-9574.1968.tb01363.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY