Sampling Richness and Qualitative Integrity: Challenges for Research With Families

Sampling is one of the most difficult and contentious aspects of qualitative research design. There are few guidelines for sampling decisions or for understanding saturation in qualitative family research. The authors frame the problematic of data quality in the selection of units of analysis and observation and consider how to enhance sample richness. They outline considerations for data quantity and sample size as well as case‐ and variable‐based approaches. With multiple examples from recent and classic studies to illustrate the consequences of sampling decisions, they explore links between saturation and validity. Finally, they encourage researchers to craft a coherent statement on qualitative integrity to demonstrate how their sampling decisions are rooted in epistemology, theory, and richness and quality of data.     

Upper Confidence Limits on Excess Risk for Quantitative Responses

The definition and observation of clear-cut adverse health effects for continuous (quantitative) responses, such as altered body weights or organ weights, are difficult propositions. Thus, methods of risk assessment commonly used for binary (quantal) toxic responses such as cancer are not directly applicable. In this paper, two methods for calculating upper confidence limits on excess risk for quantitative toxic effects are proposed, based on a particular definition of an adverse quantitative response. The methods are illustrated with data from a dose-response study, and their performance is evaluated with a Monte Carlo simulation study.     

A model for the assessment of static and dynamic factors in sexual offenders

A sample of 519 sexual offenders who were consecutive admissions to the Ontario Region of Correctional Service of Canada (CSC) were assessed with reference to a large series of variables thought to be related to sexual offending. We grouped these variables into five domains: criminality, social competence, sexual deviance, substance abuse and treatment readiness. We standardized scores on each of these domains to facilitate the calculation of total scores for each domain. We then performed a variety of analyses to determine whether these domains might constitute a reasonable model for the comprehensive evaluation of sexual offenders. Analyses indicated that overall the model received a moderate level of support.     

Binge drinking in female college students: the association of physical activity, weight concern, and depressive symptoms

As an initial step in building gender-specific binge drinking intervention programs, the authors investigated the relation of potentially modifiable factors (physical activity level, weight concern, and depressive symptoms) to binge drinking while controlling for the effects of previously established correlates of binge drinking (tobacco and marijuana use, GPA, and perception of peer alcohol use). Four-hundred-twelve college women completed an in-class survey. Multivariate analyses revealed that tobacco and marijuana use, GPA, and physical activity were significantly associated with binge drinking, whereas tobacco use and perception of peers' alcohol use were associated with more frequent binge drinking. The findings suggested that the variables associated with any binge drinking and frequency of binge drinking may differ and that binge drinking can be associated with positive health behaviors (ie, greater physical activity) as well as risky health behaviors (eg, tobacco use).     

Experimental Design of Bioassays for Screening and Low Dose Extrapolation

Relatively high doses of chemicals generally are employed in animal bioassays to detect potential carcinogens with relatively small numbers of animals. The problem investigated here is the development of experimental designs which are effective for high to low dose extrapolation for tumor incidence as well as for screening (detecting) carcinogens. Several experimental designs are compared over a wide range of different dose response curves. Linear extrapolation is used below the experimental data range to establish an upper bound on carcinogenic risk at low doses. The goal is to find experimental designs which minimize the upper bound on low dose risk estimates (i.e., maximize the allowable dose for a given level of risk). The maximum tolerated dose (MTD) is employed for screening purposes. Among the designs investigated, experiments with doses at the MTD, 1/2 MTD, 1/4 MTD, and controls generally provide relatively good data for low dose extrapolation with relatively good power for detecting carcinogens. For this design, equal numbers of animals per dose level perform as well as unequal allocations.     

Family transitions and juvenile delinquency

There is a large body of research that shows children from non-intact homes show higher rates of juvenile delinquency than children from intact homes, partially due to weaker parental control and supervision in non-intact homes. What has not been adequately addressed in the research is the influence of changes in family structure among individual adolescents over time on delinquent offending. Using the first and third waves of the National Youth Study, we assess the effect of family structure changes on changes in delinquent offending between waves through the intermediate process of changes in family time and parental attachment. Although prior research has documented adolescents in broken homes are more delinquent than youth in intact homes, the process of family dissolution is not associated with concurrent increases in offending. In contrast, family formation through marriage or cohabitation is associated with simultaneous increases in offending. Changes in family time and parental attachment account for a portion of the family formation effect on delinquency, and prior parental attachment and juvenile offending significantly condition the effect of family formation on offending.     

A Theory of Production Competence*

Production competence is an enigmatic functional phenomenon. What is it? Can it be measured? Does it affect business performance? The literature barely touches on these issues. If competence is defined as a variable rather than a fixed attribute, it can be measured by how well manufacturing's strengths and weaknesses complement the priorities of the business strategy. Since performance is a measure of how well that strategy works, there should be a definable relationship between competence and performance. This study proposes just such a relationship and promotes production competence as the theoretical link between production process and business strategy.     

Portfolio optimization: New capabilities and future methods

Summary  This paper addresses the problem of portfolio selection in finance. In many cases, currently available software to compute the efficient frontier runs into difficulty in problems with more than about 600 securities. To proceed beyond this size, it is often necessary to modify the problem in which case there is typically a loss of information. In this paper, we discuss a computer capability that can exactly compute mean-variance efficient frontiers of problems with up to 2,000 securities in very reasonable time (even if a problem’s covariance matrix is 100% dense). The paper also discusses an augmentation to the theory of portfolio selection that allows multiple objectives (such as dividends, liquidity, social responsibility, amount invested in R&D, and so forth) to be incorporated into the portfolio selection process. In such problems, the efficient set is no longer a “frontier,” but is now best described as a “surface” with the interesting property that it is composed of platelets (like on the back of a turtle). Moreover, the computer capability that can compute the exact efficient frontier of a mean-variance problem with up to 2,000 securities also has, after additional coding, the ability to compute exactly all platelets of the efficient surface of a tri-criterion portfolio problem with up to 400 securities.

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Zusammenfassung  In dieser Arbeit stellen wir einen leistungsf?higen Rechenalgorithmus vor, um den effizienten Rand (die nichtdominierten Alternativen) von Portfolio-Auswahlproblemen in der Finanzierung zu bestimmen. Wir bezeichnen den Berechnungsalgorithmus, der in Java programmiert ist, mit MPQ (multi-parametric quadratic programming). MPQ weist gegenüber bisherigen Berechnungsverfahren eine Reihe von Vorteilen auf: Es kann für umfangreiche Anwendungsf?lle genutzt werden, ist durch passable Rechenzeiten charakterisiert und kann die Menge effizienter Alternativen in einem Bruchteil bisher üblicher Rechenzeiten bestimmen.