Ballot theorem and lattice path crossings

We consider lattice paths which cross the diagonal exactly r times, and by a simple method determine the number of such paths when the endpoint is given. Then as a byproduct we easily obtain Feller's (1968, p.84) result for crossings when the length is given.     

Towards a typology of female entrepreneurs

This paper reviews some of the employment problems faced by women and examines how these difficulties might be overcome through entrepreneurship. However, recent empirical work by Goffee and Scase suggests that it is inappropriate to speak of ‘the’ female entrepreneur: there are different types of female business proprietors. Based on an empirical study of 34 aspiring female proprietors, the authors investigate the validity of Goffee and Scase's assertions. Results suggest that there are indeed different types of female entrepreneur, and that while there are some similarities between the typology developed in this paper and that presented by Goffee and Scase, there are also significant differences between them. Possible policy implications of the findings are discussed.     

Stability over time in the distribution of population forecast errors

A number of studies in recent years have investigated empirical approaches to the production of confidence intervals for population projections. The critical assumption underlying these approaches is that the distribution of forecast errors remains stable over time. In this article, we evaluate this assumption by making population projections for states for a number of time periods during the 20th century, comparing these projections with census enumerations to determine forecast errors, and analyzing the stability of the resulting error distributions over time. These data are then used to construct and test empirical confidence limits. We find that in this sample the distribution of absolute percentage errors remained relatively stable over time and data on past forecast errors provided very useful predictions of future forecast errors.     

Effects of Career Education Interventions: A Meta-Analysis

Twelve studies published between 1983 and 1996 that met the definitions for admissible studies established by Baker and Popowicz (1983) for a meta-analytic review of the effects of career education interventions were submitted to a similar meta-analytic integration. Effect sizes based on Glass's (1976) formula were determined for the current sample and were combined with the Baker and Popowicz (1983) sample, providing a sample of 30 studies and an overall effect size of 0.39.     

THE SIMMEL REVIVAL: A Challenge to American Social Science

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An Investigation of Indoor Air Contamination in Residences Above Dry Cleaners

An investigation of residences located above dry cleaning facilities was conducted to determine whether indoor and outdoor air concentrations of the dry cleaning solvent tetrachloroethene (perchloroethylene, PCE) were elevated compared to residences not near a dry cleaning facility. Data were also collected on the dry cleaners' operating conditions and equipment. Significantly elevated levels of PCE were found in the indoor air of each of six apartments located above dry cleaners compared to control residences for both day and night samples. The PCE concentrations in outdoor air near the dry cleaners were also significantly elevated compared to control locations and were lower than the concentrations measured indoors. The type of dry cleaning machine was significantly associated with the concentration of PCE found in the apartment above. A strong correlation was also found between the day and night PCE levels in the study apartments.