Refining Two-Group Multivariable Classification Models Using Univariate Optimal Discriminant Analysis*

Fisher's discriminant analysis (FDA) is often used to obtain a prediction model for dichotomous classifications on the basis of two or more independent variables. FDA provides an equation whereby values on independent variables are combined into a single predicted value (Y*) that is compared against a cutpoint and direction in order to make classifications. Theoretically, univariate optimal discriminant analysis employed on these Y* will maximize training classification accuracy. This methodology is illustrated using three examples.     

Multilevel determinants of collaboration between organised criminal groups

Collaboration between members of different criminal groups is an important feature of crime that is considered organised, as it allows criminals to access resources and skills in order to exploit illicit economic opportunities. Collaboration across criminal groups is also difficult and risky due to the lack of institutions supporting peaceful cooperation in illicit markets. Thus cross-group collaboration has been thought to take place mostly among small and transient groups. This paper determines whether and under what conditions members of different, larger organised crime groups collaborate with one another. To do so we use intelligence data from the Canadian province of Alberta, centering on criminals and criminal groups engaged in multiple crime types in multiple geographic locations. We apply a multilevel network analytical framework and exponential random graph models using Bayesian techniques to uncover the determinants of cross-group criminal collaboration. We find cross-group collaboration depends not only on co-location, but also on the types of groups to which the criminals are affiliated, and on illicit market overlap between groups. When groups are operating in the same geographically-situated illicit markets their members tend not to collaborate with one another, providing evidence for the difficulty or undesirability of cross-group collaboration in illicit markets. Conversely, members of Outlaw Motorcycle Gangs are more likely to collaborate across groups when markets overlap, suggesting the superior capacity and motivation of biker gangs to coordinate criminal activity. Our paper contributes to the understanding of criminal networks as complex, emergent, and spatially embedded market phenomena.     

Optimal Cost Sampling for Decision Making with Multiple Regression Models

This paper develops an explicit relationship between sample size, sampling error, and related costs for the application of multiple regression models in observational studies. Graphs and formulas for determining optimal sample sizes and related factors are provided to facilitate the application of the derived models. These graphs reveal that, in most cases, the imprecision of estimates and minimum total cost are relatively insensitive to increases in sample size beyond n=20. Because of the intrinsic variation of the regression model, even if larger samples are optimal, the relative change in the total cost function is small when the cost of imprecision is a quadratic function. A model-utility approach, however, may impose a lower bound on sample size that requires the sample size be larger than indicated by the estimation or cost-minimization approaches. Graphs are provided to illustrate lower-bound conditions on sample size. Optimal sample size in view of all considerations is obtained by the maximin criterion, the maximum of the minimum sample size for all approaches.     

A Multivariate Methodology for Simultaneously Capturing and Clustering Judgment Policies

This paper presents a new linear model methodology for clustering judges with homogeneous decision policies and differentiating dimensions which distinguish judgment policies. This linear policy capturing model based on canonical correlation analysis is compared to the standard model based on regression analysis and hierarchical agglomerative clustering. Potential advantages of the new methodology include simultaneous instead of sequential consideration of information in the dependent and independent variable sets, decreased interpretational difficulty in the presence of multicollinearity and/or suppressor/moderator variables, and a more clearly defined solution structure allowing assessment of a judge's relationship to all of the derived, ideal policy types. An application to capturing policies of information systems recruiters responsible for hiring entry-level personnel is used to compare and contrast the two techniques.     

A Principle for Corner Store Positioning under Intrinsic Modeling for Traffic Orientation*

This paper presents the following normative positioning principle in convenience store competition at an intersection. In countries where traffic advances on the right (left) side of the street, other things being equal, a convenience corner store should locate clockwise (counterclockwise) adjacent to the already established stores. This principle is established within a spatial framework emphasizing the relationship among the following: consumer-driver preferences, relative volume of traffic movements, and store potential at different corners. The analysis demonstrates the dependence of competitor strategy on available locations, sequence of positioning, and utility considerations.     

Health professionals’ perceptions of a midwifery model of woman-centred care implemented on a hospital labour ward

BackgroundTheoretical models as a basis for midwives’ care have been developed over recent decades. Although there are similarities between these models, their usefulness in practice needs to be researched in specific cultural contexts.AimTo explore whether, when adopted by midwives on labour wards, a midwifery model of woman-centred care (MiMo) was useful in practice from the viewpoint of a variety of health professionals.MethodsData were collected from a variety of health professionals before and after an intervention of implementating MiMo at a hospital-based labour ward in Sweden, using nine focus group interviews with a total of 43 participants: midwives (n = 16), obstetricians (n = 8), assistant nurses (n = 11) and managers (n = 8). The text from interviews was analysed using content analysis.FindingsFrom expressing no explicit need of a midwifery model of woman-centred care before the intervention, there was a shift in midwives, obstetricians and managers perceptions towards identifying advantages of using the MiMo as it gives words to woman-centred midwifery care. Such shift in perception was not found among the assistant nurses.DiscussionClarification of the various roles of health professionals is needed to develop the model. Heavy workloads and stress were barriers to implementing the model. Thus, more support is needed from organisational management.ConclusionsThe model was useful for all professional groups, except for assistant nurses. Further studies are needed in order to clarify the various professional roles and interdisciplinary collaborations in making the MiMo more useful in daily maternity care.     

FIRM EXPANSION THROUGH FRANCHISING: A MODEL AND SOLUTION PROCEDURES

This paper presents a practical model for firm expansion through franchising. The model allows the possibility of opening both company-owned and franchised stores. The objective is to maximize the expected returns to the franchisor from both types of stores, subject to the total capital outlay budget and the excess capacity available at each warehouse. A relaxation for this problem is studied and a heuristic solution procedure that makes use of this relaxation is developed. Experimental results over a wide range of problem structures show this solution methodology to be very effective, with gaps between feasible solution values and upper bounds generally in the 0 to 1 percent range. An efficient branch-and-bound code also is developed. This code is tested on problems with up to 100 potential store locations and 20 regions. It is found to be at least two orders of magnitude faster than a state-of-the-art commercial integer programming package.     

The Relationship Between Information System Planning Sophistication and Information System Success: An Empirical Assessment*

Literature on information systems (IS) planning implicitly assumes that a sophisticated IS planning process leads to greater IS success. This paper questions the exclusive reliance on this traditional belief. Instead, because IS planning requires significant organizational resources, prior IS success is essential to convince top management of the importance of IS planning sophistication. Therefore, IS success may influence IS planning sophistication. Several theoretical arguments are advanced in support of this explanation. Data from a survey of 236 academic institutions are used to empirically assess the two alternative directions of the relationship between IS planning sophistication and IS success. Four structural models including the alternative causal directions are evaluated. Two of these models are supported. Together, they imply that for a high level of IS planning sophistication, either the previous ISs should have been successful or the organization should possess advanced information technology capabilities. Thus, empirical results suggest that the explanation presented here (i.e., IS success facilitates IS planning sophistication) provides an equally good alternative to the more traditional explanation (i.e., IS planning sophistication facilitates IS success).     

Testing the Interaction Effects of Task Complexity in Computer Training Using the Social Cognitive Model

Using a Modified Social Cognitive Theory framework, this study examines the behavior modeling and lecture‐based training approaches to computer training. It extends the existing Social Cognitive Model for computer training by adding the task complexity construct to training method, prior performance, computer self‐efficacy, outcome expectations, and performance. A sample of 249 students from a large state university served as participants in a laboratory experiment that was conducted to determine the task complexity*training method and task complexity* self‐efficacy interaction effects on performance. Structural equation modeling with interaction effects was used to analyze the data. The results show that behavior modeling outperforms lecture‐based training in a measure of final performance when task complexity is high. Further, it is found that computer self‐efficacy has a greater positive effect on performance when task complexity is high than when task complexity is low. Prior performance is also found to be an important variable in the model.     

普遍主义福利思想和福利模式的相互作用及演变——解析西方福利国家困境

普遍主义是西方福利国家的思想原则。二战以后,根据这个原则西方国家创建了以北欧为代表的覆盖全体公民、综合各种福利项目的福利模式;同时西欧国家开创了如公民权、社会公正、社会进步的理念,其理念是普遍主义福利国家的形成的政治思想基础。几十年后,许多新福利思想已经创造了福利国家的新时代。这些理论是否拓展和促进了福利国家及其原则?事实是,在西方,普遍主义已经被逐渐丢掉其核心价值,代之以更实用的、折中的、妥协的福利理论,这些已经远离普遍主义的宗旨;即使依据这些新的理论,西方国家也难以走出困境的怪圈。