Generic Strategy and Performance: an Empirical Test of the Miles and Snow Typology

Previous research has considered the strategy-performance relationship in industries of relatively low degrees of dynamism and volatility. This study empirically tests the Miles and Snow typology with a dynamic, growing and volatile service industry. Results support earlier research and suggest that, considering catalogue and mail-order houses (SIC-5961), reactors did not perform as well as businesses adopting other generic strategies. However, prospectors experienced significantly higher levels of revenue growth than other businesses. Further, analysers were significantly more profitable than businesses adopting other strategies. These results suggest that combination strategies are a viable means for sustaining competitive advantage.     

The one-way analysis of variance with ordered alternatives: A modification of bartholomew's Ē2 Test

Tests of homogeneity of normal means with the alternative restricted by an ordering on the means are considered. The simply ordered case, μ₁ ≤ μ₂ ≤ ··· ≤ μ_k, and the simple tree ordering, μ₁ ≤ μ_j, for; j= 2, 3,…, k, are emphasized. A modification of the likelihood-ratio test is proposed which is asymptotically equivalent to it but is more robust to violations of the hypothesized orderings. The new test has power at the points satisfying the hypothesized ordering which is similar to that of the likelihood-ratio test provided the degrees of freedom are not too small. The modified test is shown to be unbiased and consistent.     

Two-moment approximations to some null distributions in order-restricted inference: Unequal sample sizes

Bartholomew's statistics for testing homogeneity of normal means with ordered alternatives have null distributions which are mixtures of chi-squared or beta distributions according as the variances are known or not. If the sample sizes are not equal, the mixing coefficients can be difficult to compute. For a simple order and a simple tree ordering, approximations to the significance levels of these tests have been developed which are based on patterns in the weight sets. However, for a moderate or large number of means, these approximations can be tedious to implement. Employing the same approach that was used in the development of these approximations, two-moment chisquared and beta approximations are derived for these significance levels. Approximations are also developed for the testing situation in which the order restriction is the null hypothesis. Numerical studies show that in each of the cases the two-moment approximation is quite satisfactory for most practical purposes.     

Interethnic Relationships: The Role of Social Network Diversity

We examine the degree to which ethnic diversity in social networks relates to the frequency of interethnic romantic relationships for 318 college students. In a multinomial logit, we find that the odds of having an interethnic relationship once or twice, versus never, increase significantly if the respondent has a relatively ethnically diverse friendship network, is male, and supports interethnic dating. The odds of having an interethnic relationship often, versus once or twice, are significantly higher for persons of color and when the friends of the respondent's parents are relatively diverse ethnically. Findings from open‐ended data also provide support for a social network perspective, and point to the processes by which networks, gender, and ethnicity shape interethnic courtship.     

An application of a multi‐stage strategy involving confidence intervals to evaluate whether a response rate is favourable or not

In early clinical development of new medicines, a single‐arm study with a limited number of patients is often used to provide a preliminary assessment of a response rate. A multi‐stage design may be indicated, especially when the first stage should only include very few patients so as to enable rapid identification of an ineffective drug. We used decision rules based on several types of nominal confidence intervals to evaluate a three‐stage design for a study that includes at most 30 patients. For each decision rule, we used exact binomial calculations to determine the probability of continuing to further stages as well as to evaluate Type I and Type II error rates. Examples are provided to illustrate the methods for evaluating alternative decision rules and to provide guidance on how to extend the methods to situations with modifications to the number of stages or number of patients per stage in the study design. Copyright © 2004 John Wiley & Sons, Ltd.     

Majority Rules? The Effects of School Ethnic Composition on Substance Use by Mexican Heritage Adolescents

This article examines key aspects of the school environment - its composition by ethnicity and acculturation - as important social contexts for understanding Mexican immigrant and Mexican American adolescents' drug use norms and behaviors. Results are presented based on surveys completed by Mexican-background students from 35 Phoenix. Arizona middle schools, whose enrollment ranged from a numerical minority to an overwhelming majority. Multivariate mixed models tested for the influence of school ethnic composition measures on substance use outcomes, while accounting for individual level predictors and for the nesting of data at the school level. The proportional representation of Latinos in the school was not a factor in an individual's drug use norms or drug use for the sample overall. Once students were broken down by acculturation status, however, ethnic composition had an effect. Less acculturated Mexican heritage students in schools with higher proportions of Latino students reported less substance use and less adherence to pro-drug norms. Further investigation using other measures of ethnic composition suggested that these effects were attributable to the larger presence of less acculturated Latinos in the school rather than more acculturated Latino students. These school-level effects support the individual-level results indicating that less acculturated Mexican American students face less daunting substance use risks. The results suggest that ethnic group size, but not necessarily numerical predominance, matters and that within-group differences influence the effect of a particular ethnic group's presence in the school. In other words, the majority does not always rule. These findings are interpreted using the concepts of segmented assimilation and school level social capital.     

Biomedical applications for a generalized linear functional Poisson model

Many medical and biological studies involve response in the form of Poisson counts which can bemodelled using explanatory variables which also arise from count data. If the explanatory variables are observable without error (also as Poisson counts) we have a generalized linear model with a logarithmic link function and Poisson error structure. If,however, some of the explanatory variables are not directly observable, but arise with superimposed errors (again of Poisson form), the model is of a new type:a generalised linear functional Poisson model. In this paper,maximum likelihood estimates of the parameters of this model are determined along with the information matrix which (on noting its particular patterned form) is amenable to inversion in explicit form. Methods are proposed of an iterative type for computing estimates of the parameters and of their variational properties (e.g. standard errors) for this model, which also has application in other fields such as road traffic studies.     

Health and Social Services Planning

The authors outline joint planning between health and social services since 1974, examining the joint planning meetings of two different types. They identify certain features of small group meetings which could ease joint planning arrangements.