Testing regression lack of fit without replication: a tutorial around Minitab's XLOF procedures

The tutorial is concerned with two types of test for the general lack of fit of a linear regression model, as found in the Minitab software package, and which do not require replicated observations. They aim to identify non-specified curvature and interaction in predictors, by comparing fits over the predictor region divided into two parts. Minitab's regression subcommand XLOF which gives the tests is only briefly documented in the manual and, unlike virtually all other statistical procedures in the software, it is not standard and cannot be readily found in textbooks. The two types of test are described here; they concern the predictors one-at-a-time and the predictors all-at-once. An example of their use is given. A suite of macros is available which reproduces the results of the XLOF tests in much more detail than is given by the XLOF subcommand.     

Curved Chaotic Map Time Series Models and Their Stochastic Reversals

This paper considers two types of chaotic map time series models, including the well-known tent, logistic and binary-shift maps as special cases; these are called curved tent and curved binary families. Deterministic behaviour is investigated by invariant distributions, Lyapunov exponents, and by serial dependency. Stochastic time reversal of the families is shown to produce models which have a broader range of stochastic and chaotic properties than their deterministic counterparts. The marginal distributions may have concentrations and restricted supports and are shown to be a non-standard class of invariant distribution. Dependenc y is generally weaker with the reversed stochastic models. The work gives a broad statistical account of deterministic and stochastically reversed map models, such as are emerging in random number generation, communica tion systems and cryptography     

Theorizing Managerial Work: a Pragmatic Pluralist Approach to Interdisciplinary Research

Management research is especially open to the benefits of using insights from a variety of social science disciplines but it should not use these indiscriminately. A strategy of pragmatic pluralism is proposed as a way of ensuring that concepts taken from different social science paradigms or disciplines are drawn together into a single coherent perspective to shape the particular study to which they relate. This is illustrated with reference to an ethnographic study of managerial work carried out by the author.     

在公共服务递送中运营共同生产：服务蓝图的贡献

本文认为,公共服务应从以产品为主导的逻辑转向服务途径。通过采取服务导向,公共服务递送的经验性、组织间和系统性,以及作为共同生产者的服务使用者角色,将一同被考虑。论文将通过服务蓝图的应用,解释共同生产如何操作。并介绍了高等教育中的一个案例。在这一案例中,蓝图的创建将师生汇聚在一起,专注于学生入学的设计,从而改善学生体验,并支持共同生产。      

Identity Development in an International Transracial Adoptive Family: A 5-Year Case Study

Our case study focused on the adoptive identity development of two female Chinese adoptees over the course of five years (from when they were 7 and 9 until they were 12 and 14 years old, respectively). The study investigated the adoptive parent’s and family identities through six interviews with the adoptive mother, adoptees’ behavioral adjustment reported by the mother, two unstructured observations, and exploration of adoptees’ narratives. The study was guided by a narrative-based framework situated with the cultural socialization approach. Results highlight four central themes: 1) becoming Chinese-Americans; 2) meaning related to adoption is both spoken and unspoken; 3) a we-ness identity, and 4) social-cultural contexts of identity work. Findings demonstrate the incorporation of adoption and the adoptees’ race and culture into the adoptive parent’s and family identities. Findings further illuminate that one’s identity is developed within personal, familial, and social-cultural contexts.     

Macro-Economic Factors in Credit Risk Calculations: Including Time-Varying Covariates in Mixture Cure Models

The prediction of the time of default in a credit risk setting via survival analysis needs to take a high censoring rate into account. This rate is because default does not occur for the majority of debtors. Mixture cure models allow the part of the loan population that is unsusceptible to default to be modeled, distinct from time of default for the susceptible population. In this article, we extend the mixture cure model to include time-varying covariates. We illustrate the method via simulations and by incorporating macro-economic factors as predictors for an actual bank dataset.