Domains of convergence for the EM algorithm: a cautionary tale in a location estimation problem

The EM algorithm is a popular method for maximizing a likelihood in the presence of incomplete data. When the likelihood has multiple local maxima, the parameter space can be partitioned into domains of convergence, one for each local maximum. In this paper we investigate these domains for the location family generated by the t-distribution. We show that, perhaps somewhat surprisingly, these domains need not be connected sets. As an extreme case we give an example of a domain which consists of an infinite union of disjoint open intervals. Thus the convergence behaviour of the EM algorithm can be quite sensitive to the starting point.     

DO DRINKERS KNOW WHEN TO SAY WHEN? AN EMPIRICAL ANALYSIS OF DRUNK DRIVING

This paper presents empirical evidence that an individual's decision to drive while drunk is negatively affected by the expected full price of driving drunk. The analysis uses a unique data set containing information on self-reported drunk driving matched to state-level drunk driving policies as well as to state excise taxes on beer. These are hypothesized and found to affect drunk driving. Further, we find interesting racial differences but surprisingly small differences by gender in the effect of socioeconomic and policy variables on drunk driving propensities.     

The Meaning of Work and Love: Career Issues and Interventions

Examining concepts about work and love can help people increase their career success and life satisfaction. Career counselors may initiate this examination by eliciting clients' concepts about work and love. After hearing a client's ideas about work and love, counselors can compare this personal meaning to the social meaning of work and love. When this comparison reveals dysfunctional beliefs about work and love, counselors can link these beliefs to their client's career concerns. Such a linkage typically provokes a cognitive dissonance that motivates clients to modify their beliefs. Counselors can facilitate meaning modification by using client-centered and social influence techniques.     

First Nations and community economic development: a case study

A training project in a northern Canadian community providedan opportunity to examine participatory planning approachesand the meaning of work in First Nations communities. Focusgroups conducted three years after the unsuccessful interventionof a community economic development (CED) project suggest thatcomplex factors such as lack of support from community leadersand rate of pay for workers determine whether CED is alwaysappropriate in northern, First Nations contexts.     

Employment growth in high-tech new ventures

We specify and estimate a model of the early employment growth of technology-driven new ventures. Our estimated model is derived from labor demand theory. A data set of 100 German firms is used to conduct this analysis. The study’s findings support the relevance of the theory as applied to these nascent firms. Employment growth is significantly enhanced in ventures exhibiting high profits, experienced founders, formal information processes, and outsourced product distribution. Our findings also confirm aspects of Penrose’s theory of firm growth suggesting that transactions costs associated with larger founder teams may inhibit employment growth.     

亚当·斯密的公路经济理论

研究了亚当.斯密公路经济理论的几个重要观点:公路的选址和规模、资金筹措、运营和征收车辆通行税等,并分析了车辆通行税管理权划归中央或地方的标准,得出建立监督机制、关注乡村公路和偏远公路有利于公路发展的结论,这对中国公路建设理论与实践有重要的借鉴作用。