Group technology,cells and flow-lines

The similarities between the Group Technology (GT) Cell system and flow-line production are explored, with particular reference to the nature of the production systems, and worker organization. Several factors are identified which not only distinguish flow-line and GT cell design, but also give rise to the relative inefficiency of GT cell systems. The nature of the work-group provided in a GT cell is contrasted with functional work-groups of the type advocated for flow-line working, the benefits of the latter being found to be available in, but not necessarily provided by, the cell system.     

Some solutions to the multivariate Behrens–Fisher problem for dissimilarity‐based analyses

The essence of the generalised multivariate Behrens–Fisher problem (BFP) is how to test the null hypothesis of equality of mean vectors for two or more populations when their dispersion matrices differ. Solutions to the BFP usually assume variables are multivariate normal and do not handle high‐dimensional data. In ecology, species' count data are often high‐dimensional, non‐normal and heterogeneous. Also, interest lies in analysing compositional dissimilarities among whole communities in non‐Euclidean (semi‐metric or non‐metric) multivariate space. Hence, dissimilarity‐based tests by permutation (e.g., PERMANOVA, ANOSIM) are used to detect differences among groups of multivariate samples. Such tests are not robust, however, to heterogeneity of dispersions in the space of the chosen dissimilarity measure, most conspicuously for unbalanced designs. Here, we propose a modification to the PERMANOVA test statistic, coupled with either permutation or bootstrap resampling methods, as a solution to the BFP for dissimilarity‐based tests. Empirical simulations demonstrate that the type I error remains close to nominal significance levels under classical scenarios known to cause problems for the un‐modified test. Furthermore, the permutation approach is found to be more powerful than the (more conservative) bootstrap for detecting changes in community structure for real ecological datasets. The utility of the approach is shown through analysis of 809 species of benthic soft‐sediment invertebrates from 101 sites in five areas spanning 1960 km along the Norwegian continental shelf, based on the Jaccard dissimilarity measure.     

Population correlation matrices for sampling experiments

A procedure is given for generating correlation matrices which can be used as population correlation matrices for sampling experiments. The algorithm specifies the eigenvalues and randomly selects a correlation matrix from the class of all correlation matrices which possess these same eigenvalues. It is possible to obtain a set of correlation matrices which are indexed by the degree of interdependence among the variables by parameterizing the eigenvalues with a single parameter. An example is the case in which the eigenvalues form a geometric progression. Examples are given and an application to the problem of stopping rules in stepwise regression is discussed. Other applications are also briefly discussed.     

An investigation of lag identification tools for vector nonlinear time series

Exploratory methods for determining appropriate lagged vsrlables in a vector nonlinear time series model are investigated. The first is a multivariate extension of the R statistic considered by Granger and Lin (1994), which is based on an estimate of the mutual information criterion. The second method uses Kendall's ρ and partial ρ statistics for lag determination. The methods provide nonlinear analogues of the autocorrelation and partial autocorrelation matrices for a vector time series. Simulation studies indicate that the R statistic reliabiy identifies appropriate lagged nonlinear moving average terms in a vector time series, while Kendall's ρ and partial ρ statistics have some power in identifying appropirate lagged nonlinear moving average and autoregressive terms, respectively, when the nonlinear relationship between lagged variables is monotonic. For illustration, the methods are applied to set of annual temperature and tree ring measurements at Campito Mountain In California.     

Serial Publications in the Center for Research Libraries

This article has been limited to describing the Center's activities in regard to serial publications. The reader should be reminded that the materials described in this article form only a part of the Center's collection. Excluding government documents, serial publications alone account for about 600,000 of the over 3,000,000 volumes held by the Center. The Center's printed Catalogue presently consists of 12 volumes of monographic titles, but only three volumes of serial titles. In addition to this, the Center holds over 500,000 foreign doctoral dissertations, 85,000 textbooks, 45,000 children's books, 125,000 college catalogs and several smaller collections of monographic materials which are shelf cataloged and thus do not appear in the printed Catalogue. erial publications thus form only one part of the Center's total collection. That it is a significant part is indicated by the fact that the publications described in this article, current issues and backfiles of journals and newspapers, account for nearly 60% of the material borrowed from the Center.

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