摘要:

This paper examines the method of estimating the heritable component of behavioural traits by comparing observed similarities between pairs of MZ (monozygotic) twins as opposed to DZ (dizygotic) twins. The technique ofsensitivity analysisis used to investigate the importance of assumptions made to calculate heritability estimates. This permits not only the investigation of specific assumptions, but also the effects of different combinations of assumptions. The assumptions examined include: the level of assortative mating, degree of intra‐pair environmental similarity of MZ as opposed to DZ twins, and the presence of genotype‐environment covariance. It is noted that estimates of genetic variance—although large—are sensitive to small changes in these assumptions, and that different combinations of assumptions can produce similar estimates of genetic variance. Although this work is effected within the classical twin method, its implications are also valid for more sophisticated analyses of the ‘nature‐nurtu

ISSN:0007-1102    

DOI:10.1111/j.2044-8317.1974.tb00523.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

The concept of a spanning tree for a weighted graph is used to characterize several methods of clustering a set of objects. In particular, most of the paper is devoted to stating relationships between spanning trees, single‐link and complete‐link hierarchical clustering, network flow and two divisive clustering procedures. Several related topics using the notion of a spanning tree are also mentio

ISSN:0007-1102    

DOI:10.1111/j.2044-8317.1974.tb00524.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Solutions were sought for problems in applying the Birnbaum three‐parameter logistic mental test model through Bayesian tailored testing. Both empirical and Monte Carlo data were utilized. The general conclusions were: (1) Although conventional tests are not generally good for tailored testing, some individual items are excellent. (2) It may be possible to develop methods of graphic parameter estimation to the point where expensive maximum‐likelihood methods can be by‐passed. (3) An item bank for tailored testing must have a sufficiently large number of items whose difficulties are uniformly distributed and whose discriminatory powers are high. (4) The use of prior information in Bayesian tailored testing does not lead to a substantial reduction in the number of items needed, unless prior information is unrealistically accurate. (5) The standard error of the estimate of ability has certain characteristics which may have important consequences for tailored testing under certain condi

ISSN:0007-1102    

DOI:10.1111/j.2044-8317.1974.tb00525.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

A new procedure for determining Slater'siand all nearest adjoining orders is described and its use illustrated.

ISSN:0007-1102    

DOI:10.1111/j.2044-8317.1974.tb00526.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

The paper deals with the adjustment of examiners’ marks for a single test when the scripts are marked by several independent examiners, each of whom is assigned a different but statistically equivalent set of script

ISSN:0007-1102    

DOI:10.1111/j.2044-8317.1974.tb00527.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

The desirability that scores on a preference scale should be additive is first demonstrated. It is then shown that when the logistic transformation of the proportion of preferences for an object in a paired‐comparison experiment is used as a scoring device additivity is achieved when preferences between pairs of objects are made independently and the preferences are consistent. An example is given to show how the analysis of paired‐comparison data may conveniently be carried out, a test of additivity performed, and scale values for the objects deri

ISSN:0007-1102    

DOI:10.1111/j.2044-8317.1974.tb00528.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

The robustness of three multiple‐comparison procedures (multiplettest, Tukey WSD and SchefféStest) to the violation of the homogeneous population variance assumption was investigated using three different standard error estimates. These estimates were (1) the square root of two mean square within/n, (2) the standard error of the traditionalttest and (3) the standard error of the Behrens‐Fishert′ statistic. The procedures were highly robust to variance heterogeneity using the Behrens‐Fisher standard error estimate. The procedures were considerably less robust using MSW. The universal use of the Behrens‐Fisher statistic with the Welch solution for critical values is r

ISSN:0007-1102    

DOI:10.1111/j.2044-8317.1974.tb00529.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

A number of writers have regarded difficulty factors as arising from the misbehaviour, in some sense, of correlation coefficients for binary data when the binary variables have varying difficulty levels. McDonald (1965) argued that difficulty factors are due to non‐linear item characteristic curves rather than difficultyper se, but did not give an example using binary data. An artificial experiment is described in which non‐linear item characteristic curves yield a difficulty factor, whereas linear item characteristic curves do not, even when in the latter case the items differ markedly in difficulty and phi coefficients are emplo

ISSN:0007-1102    

DOI:10.1111/j.2044-8317.1974.tb00530.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Harris&Kaiser's (1964) class of oblique factor solutions, referred to asCase II, is reviewed and further developed. Certain features of the component matrices are explicated, and an iterative procedure is presented for their simultaneous solution. Illustrative examples are given, based on both this iterative procedure and other Case II formulations. Implications for practice and further research are discussed.

ISSN:0007-1102    

DOI:10.1111/j.2044-8317.1974.tb00531.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Gradient methods are employed in orthogonal and oblique analytic rotation. Constraints are imposed on the elements of the transformation matrix by means of reparameterizations.

ISSN:0007-1102    

DOI:10.1111/j.2044-8317.1974.tb00532.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY