The TOWS matrix—A tool for situational analysis

This article has two main purposes. One is to review general considerations in strategic planning and the second to introduce the TOWS Matrix for matching the environmental threats and opportunities with the company's weaknesses and especially its strengths. These factors per se are not new; what is new is systematically identifying relationships between these factors and basing strategies on them. There is little doubt that strategic planning will gain greater prominence in the future. Any organization—whether military, product-oriented, service-oriented or even governmental—to remain effective, must use a rational approach toward anticipating, responding to and even altering the future environment.     

Adaptation of Tastes to Constraints

This paper examines a model in which people’s preferences adjust to changes in their relative ability to attain various goals. Preference changes are modeled as changes in the configuration of weights (or values) attached to these goals. The model permits to explain common prototype changes of preferences such as the ‘sour grapes’ or the ‘overcompensating’ phenomenon. It is found that whether the first or the second phenomenon occurs depends on whether a goal is easy or difficult to substitute by other goals. If two goals are sufficiently strong substitutes for each other, no weight will be placed on that goal which is harder to attain. The results readily apply to the standard microeconomic set-up involving goods and prices, rather than abstract goals and abilities. In this case, one implication of the model is that only a subset of the overall commodity space is relevant for everyday consumer choice, which reduces the complexity of the choice procedure. The model also permits to explain how new and unfamiliar products are incorporated into the consumer’s preference pattern.     

Book reviews

Disputed Histories: Imagining New Zealand's Pasts edited by Tony Ballantyne and Brian Moloughney. University of Otago Press, Dunedin. 2006. 283 p. NZ$49.95 (paperback). ISBN 1877276161.

Historical Frictions: Maori Claims and Reinvented Histories by Michael Belgrave. Auckland University Press, Auckland. 2005. 388 p. NZ$49.95 (paperback). ISBN 1869403207.

New Zealand Identities: Departures and Destinations edited by James H Liu, Tim McCreanor, Tracey McIntosh, and Teresia Teaiwa. Victoria University Press, Wellington. 2005. 304 p. NZ$39.95 (paperback). ISBN 0864735170.

Revolution: The 1913 Great Strike in New Zealand, edited by Melanie Nolan. Canterbury University Press, Christchurch. 2006. 320 p. NZ$34.95 (paperback). ISBN 1877257400.

Sexuality Down Under: Social And Historical Perspectives edited by Allison Kirk‐man and Pat Moloney. University of Otago Press, Dunedin. 2006. 301 p. NZ$39.95 (paperback). ISBN 1877372102.

Geographies of Globalization by Warwick E. Murray. Routledge, London and New York. 2006. 392 p. NZ$69.95 (paperback). ISBN 0415317991.     

Optimal paired comparison designs for first-order interactions

In many fields of applications paired comparisons are used in which either full or partial profiles of the alternatives are presented. For this situation we introduce an appropriate model and derive optimal designs in the presence of interactions when all attributes have the same number of levels.     

Best quadratic and positive semidefinite unbiased estimation of the variance matrix of the multivariate normal distribution

A BQPUE (best quadratic and positive semidefinite unbiased estimator) of the matrix V for the distribution vec X^′∽N_np(vec M^′, U?V) is being given. It is unique, although still depending on U and M. When U = I and M = (μ,…,μ), we get a well-known (unique) result not depending on M.     

Reviews

Theory and Decision -     

Estimation of the SURE model

The paper presents the essentials of the SURE model and the estimation of its parameters β and ω. Two alternative compact representations of the model are being used. The parameter β is estimated by least squares (LS), generalized least squares (GLS) and maximum likelihood (ML) (under normality). For ω two estimators are being considered, viz an LS-related estimator and a maximum likelihood estimator (under normality). Attention is being given to the study of asymptotic properties of all estimators examined. It turns out that the LS-related and ML estimators of ω follow the same asymptotic (normal) distribution. Efficiency comparisons for the various estimators of β conclude the paper.     

The blocking job shop with rail-bound transportation

The blocking job shop with rail-bound transportation (BJS-RT) considered here is a version of the job shop scheduling problem characterized by the absence of buffers and the use of a rail-bound transportation system. The jobs are processed on machines and are transported from one machine to the next by mobile devices (called robots) that move on a single rail. The robots cannot pass each other, must maintain a minimum distance from each other, but can also “move out of the way”. The objective of the BJS-RT is to determine for each machining operation its starting time and for each transport operation its assigned robot and starting time, as well as the trajectory of each robot, in order to minimize the makespan. Building on previous work of the authors on the flexible blocking job shop and an analysis of the feasible trajectory problem, a formulation of the BJS-RT in a disjunctive graph is derived. Based on the framework of job insertion in this graph, a local search heuristic generating consistently feasible neighbor solutions is proposed. Computational results are presented, supporting the value of the approach.