Euler buckling in a wheelbarrow obstacle course: a catastrophe with complex lag

This article studies human physical work capacity under increasing load from a general systems theory perspective. There are several points of generalization between the structure of nonliving (building materials) and living systems (humans) with respect to stress, strain, and fatigue. A catastrophe model for Euler buckling was transposed and tested for human performance in a wheelbarrow obstacle course under varying loads. Subjects were 129 employees of a Midwest manufacturing plant. A cusp model was hypothesized and verified (R2 = .68, control R2 = .11) where vertical load was the asymmetry factor, and body balance, height, and sex-related differences all contributed to bifurcation. A catastrophe model in codimension 10 was also invoked to explain memory in the system. Principal control variables were exercise habits, weight, balance, and sex-related differences (R2 = .75). The core model of human load-to-failure was concluded to be similar to that for Euler buckling: additional complexities were discovered which were attributed in part to systemic memory. Discussion points included the use of large dimension catastrophe models for problems involving complex lag effects, and the transposability of the model to the organizational systemic level.     

It Is Not Just About Location: Infants Perseverate to Container Shape During Object Search

In searching for a toy hidden at a new location, infants will err by searching at the previously correct location. This study investigated the possibility that 8.5‐month‐old infants would perseverate on the basis of other visual features by which covers could be individuated. Infants saw a toy hidden under 1 of 2 distinctly shaped covers. Following successful retrievals from the Shape A cover, infants saw the toy hidden under the Shape B cover. On this B trial, the covers were at locations that had not been baited on the preceding trials, precluding location perseveration. The infants erred by choosing the unbaited Shape A cover more often than control infants presented with 1 type of cover throughout. The findings suggest that infants perseverate to cover shape and are form biases biased toward cover shape even when location information is sufficient to support retrieval.     

Social Policy at the 2004 Election

Social policy appeared to be a key battleground at the 2004 Australian Federal election. Opposition Leader Latham announced major policies on Medicare, family support and taxation, and schools funding during the election campaign. Using sample survey data from the Australian Election Study 2004, this paper analyses how these policies may have influenced voters. In brief, although a significant proportion of electors identified these issues as being extremely important to them when they were deciding about how to vote, many made up their mind about how to vote around the time of the announcement of the election or before. This mitigated the potential effect that these major policies could have on the election outcome. Nevertheless, these policies were important and Labor had a significant policy advantage amongst those who were late deciders about how to cast their vote.     

Measuring the complexity of generalized linear hierarchical models

Measuring a statistical model's complexity is important for model criticism and comparison. However, it is unclear how to do this for hierarchical models due to uncertainty about how to count the random effects. The authors develop a complexity measure for generalized linear hierarchical models based on linear model theory. They demonstrate the new measure for binomial and Poisson observables modeled using various hierarchical structures, including a longitudinal model and an areal‐data model having both spatial clustering and pure heterogeneity random effects. They compare their new measure to a Bayesian index of model complexity, the effective number p_D of parameters (Spiegelhalter, Best, Carlin & van der Linde 2002); the comparisons are made in the binomial and Poisson cases via simulation and two real data examples. The two measures are usually close, but differ markedly in some instances where p_D is arguably inappropriate. Finally, the authors show how the new measure can be used to approach the difficult task of specifying prior distributions for variance components, and in the process cast further doubt on the commonly‐used vague inverse gamma prior.     

Determination of an attribute single sampling scheme

SUMMARY This paper presents procedures for the selection of a new sampling scheme called 'single sampling scheme' (SSS). It presents a compact table for the selection of an SSS indexed by various combinations of entry parameters. The advantages of SSSs are discussed. The basis for the construction of the table is also given.