Two Graphical Techniques Useful in Detecting Correlation Structure in Repeated Measures Data

Analysis of repeated measures data using a mixed model includes specifying a form for the covariance matrix of the within-subject observations. This reduction in the number of estimated parameters from the unspecified structure may improve the efficiency of inferences made. An implementation of this technique has been incorporated in the MIXED procedure of the SAS® statistical package, and includes a wide range of options for the structure of the covariance matrix. It is demonstrated that draftman's display plots and/or plots in a coordinate system with parallel axes can aid in visualizing the dispersion structure.     

Siting Samplers to Minimize Expected Time to Detection

We present a probabilistic approach to designing an indoor sampler network for detecting an accidental or intentional chemical or biological release, and demonstrate it for a real building. In an earlier article, Sohn and Lorenzetti developed a proof of concept algorithm that assumed samplers could return measurements only slowly (on the order of hours). This led to optimal “detect to treat” architectures that maximize the probability of detecting a release. This article develops a more general approach and applies it to samplers that can return measurements relatively quickly (in minutes). This leads to optimal “detect to warn” architectures that minimize the expected time to detection. Using a model of a real, large, commercial building, we demonstrate the approach by optimizing networks against uncertain release locations, source terms, and sampler characteristics. Finally, we speculate on rules of thumb for general sampler placement.     

Empirical bayes estimation of the binomial parameter n

Estimation of the prior distribution of the binomial parameter nbased on a system of orthogonal polynomials, the Poisson-Charlier polynomials, is studied. It is shown that the resulting estimator is mean squared consistent with rate O(N ^ε-1), where Nis the sample size and ε> 0 is arbitrarily small.     

Another twist on the equality of OLS and GLS

We give a neccessary and sufficient condition for the equality of theOLS andGLS estimator of a subset of the regression coefficients in a linear model.     

THE EXPERIMENTS OF REDUCED WORKING HOURS IN FINLAND

This paper examines experiments of shorter working hours in Finnish municipalities between 1996 and 1998 in terms of the effects of the experiments on work–family interaction and which of the ways of reducing working time had the most positive effect. We analyse the experiment in respect of the Finnish working time regime, and in addition, from the perspective of community time. The analysis combines questionnaire and interview data. The results indicated that the experiment had a positive effect on work–family interaction. Six-hour shifts, in comparison to other forms of working time reductions, had the strongest impact on the decrease in conflict arising from work and affecting family. The interviews demonstrated various effects of the working time experiment on family, including the negative effects caused by unsocial working hours and the loss of time autonomy at work among the highly educated. Furthermore, reduced working hours in a culture based on the principle of full-time work caused some negative effects, such as feelings of guilt. The impact of the experiment on community time depended on the way the experiment was implemented.     

Images of Success: How Illinois Farmers Define the Successful Farmer1

Abstract Farmers' views of farming success help frame their responses to information about farming, including alternative agriculture. A Q-analysis of 68 commercial farmers' subjective images of the successful farmer and the relative importance they accord different personal values and characteristics revealed four “model” images of the successful farmer. The Steward recognizes a moral responsibility to sustain land resources; the Manager succeeds largely by virtue of analytical skill; the Conservative's main goal is long-term preservation of the farm business; and the Agrarian values the rural life style and community participation. Farmers holding the Steward image tended to be older and to farm fewer acres; those with the Manager image included a large proportion of less experienced farmers. Approximately 40 percent of the farmers' views of success did not fit any of the four “model” images. Analysis of the findings suggests that images of success may be associated with life stage or generational differences in farming goals and values.