Multilevel analyses in marketing research:differentiating analytical outcomes

Marketing scholars are increasingly recognizing the importance of investigating phenomena at multiple levels. However, the analyses methods that are currently dominant within marketing may not be appropriate to dealing with multilevel or nested data structures. We identify the state of contemporary multilevel marketing research, finding that typical empirical approaches within marketing research may be less effective at explicitly taking account of multilevel data structures than those in other organizational disciplines. A Monte Carlo simulation, based on results from a previously published marketing study, demonstrates that different approaches to analysis of the same data can result in very different results (both in terms of power and effect size). The implication is that marketing scholars should be cautious when analyzing multilevel or other grouped data, and we provide a discussion and introduction to the use of hierarchical linear modeling for this purpose.

Assessing pupil and school performance by non-parametric and parametric techniques

Often observations are nested within other units. This is particularly the case in the educational sector where school performance in terms of value added is the result of school contribution as well as pupil academic ability and other features relating to the pupil. Traditionally, the literature uses parametric (i.e. it assumes a priori a particular function on the production process) Multi-Level Models to estimate the performance of nested entities. This paper discusses the use of the non-parametric (i.e. without a priori assumptions on the production process) Free Disposal Hull model as an alternative approach. While taking into account contextual characteristics as well as atypical observations, we show how to decompose non-parametrically the overall inefficiency of a pupil into a unit specific and a higher level (i.e. a school) component. By a sample of entry and exit attainments of 3017 girls in British ordinary single sex schools, we test the robustness of the non-parametric and parametric estimates. We find that the two methods agree in the relative measures of the scope for potential attainment improvement. Further, the two methods agree on the variation in pupil attainment and the proportion attributable to pupil and school level.

Statnote 9: The one-way analysis of variance (random effects model)

There is an alternative model of the 1-way ANOVA called the 'random effects' model or ‘nested’ design in which the objective is not to test specific effects but to estimate the degree of variation of a particular measurement and to compare different sources of variation that influence the measurement in space and/or time. The most important statistics from a random effects model are the components of variance which estimate the variance associated with each of the sources of variation influencing a measurement. The nested design is particularly useful in preliminary experiments designed to estimate different sources of variation and in the planning of appropriate sampling strategies.

The design of fault tolerant software for loosely coupled distributed systems

Requirements for systems to continue to operate satisfactorily in the presence of faults has led to the development of techniques for the construction of fault tolerant software. This thesis addresses the problem of error detection and recovery in distributed systems which consist of a set of communicating sequential processes. A method is presented for the `a priori' design of conversations for this class of distributed system. Petri nets are used to represent the state and to solve state reachability problems for concurrent systems. The dynamic behaviour of the system can be characterised by a state-change table derived from the state reachability tree. Systematic conversation generation is possible by defining a closed boundary on any branch of the state-change table. By relating the state-change table to process attributes it ensures all necessary processes are included in the conversation. The method also ensures properly nested conversations. An implementation of the conversation scheme using the concurrent language occam is proposed. The structure of the conversation is defined using the special features of occam. The proposed implementation gives a structure which is independent of the application and is independent of the number of processes involved. Finally, the integrity of inter-process communications is investigated. The basic communication primitives used in message passing systems are seen to have deficiencies when applied to systems with safety implications. Using a Petri net model a boundary for a time-out mechanism is proposed which will increase the integrity of a system which involves inter-process communications.

Kindness is the parent of kindness: reciprocity in the UK call centre workplace

This research developed, proposed and tested an integrated psychological process to performance model. The model utilized the overarching theory of social exchange to incorporate the climate perceptions and affective reactions of 3,012 employees across 88 UK call centres. In the pursuit of parsimony, a review of the applied psychology literature gave rise to a model where the path between global service climate and contextual performance was fully mediated by, first, perceived organizational support, second, job satisfaction and third, affective commitment. The resulting integrated and parsimonious model was tested via SEM and the mediation hypotheses were tested via a series of nested competing models. A moderate fit and partial, rather than full, mediation were reported. Nested Competing Model 4 proved to be the most parsimonious and to have the best fit. It is important to recognise, however, that Nested Competing Model 4 is not intended to be the most comprehensive model (which would include all significant paths), but a more practically useful one (i.e. parsimonious), that focuses on the main relationships.

Compositional semantics of dataflow networks with query-driven communication of exact values

We develop and study the concept of dataflow process networks as used for exampleby Kahn to suit exact computation over data types related to real numbers, such as continuous functions and geometrical solids. Furthermore, we consider communicating these exact objectsamong processes using protocols of a query-answer nature as introduced in our earlier work. This enables processes to provide valid approximations with certain accuracy and focusing on certainlocality as demanded by the receiving processes through queries. We define domain-theoretical denotational semantics of our networks in two ways: (1) directly, i. e. by viewing the whole network as a composite process and applying the process semantics introduced in our earlier work; and (2) compositionally, i. e. by a fixed-point construction similarto that used by Kahn from the denotational semantics of individual processes in the network. The direct semantics closely corresponds to the operational semantics of the network (i. e. it iscorrect) but very difficult to study for concrete networks. The compositional semantics enablescompositional analysis of concrete networks, assuming it is correct. We prove that the compositional semantics is a safe approximation of the direct semantics. Wealso provide a method that can be used in many cases to establish that the two semantics fully coincide, i. e. safety is not achieved through inactivity or meaningless answers. The results are extended to cover recursively-defined infinite networks as well as nested finitenetworks. A robust prototype implementation of our model is available.

Statnote 30 : The one-way analysis of variance (ANOVA):fixed effects model

In Statnote 9, we described a one-way analysis of variance (ANOVA) ‘random effects’ model in which the objective was to estimate the degree of variation of a particular measurement and to compare different sources of variation in space and time. The illustrative scenario involved the role of computer keyboards in a University communal computer laboratory as a possible source of microbial contamination of the hands. The study estimated the aerobic colony count of ten selected keyboards with samples taken from two keys per keyboard determined at 9am and 5pm. This type of design is often referred to as a ‘nested’ or ‘hierarchical’ design and the ANOVA estimated the degree of variation: (1) between keyboards, (2) between keys within a keyboard, and (3) between sample times within a key. An alternative to this design is a 'fixed effects' model in which the objective is not to measure sources of variation per se but to estimate differences between specific groups or treatments, which are regarded as 'fixed' or discrete effects. This statnote describes two scenarios utilizing this type of analysis: (1) measuring the degree of bacterial contamination on 2p coins collected from three types of business property, viz., a butcher’s shop, a sandwich shop, and a newsagent and (2) the effectiveness of drugs in the treatment of a fungal eye infection.

Long memory and multifractality:a joint test

The properties of statistical tests for hypotheses concerning the parameters of the multifractal model of asset returns (MMAR) are investigated, using Monte Carlo techniques. We show that, in the presence of multifractality, conventional tests of long memory tend to over-reject the null hypothesis of no long memory. Our test addresses this issue by jointly estimating long memory and multifractality. The estimation and test procedures are applied to exchange rate data for 12 currencies. Among the nested model specifications that are investigated, in 11 out of 12 cases, daily returns are most appropriately characterized by a variant of the MMAR that applies a multifractal time-deformation process to NIID returns. There is no evidence of long memory.

Obstacles and solutions to maximising urban biodiversity throughout the lifecycles of major developments in England

Thus far, achieving net biodiversity gains through major urban developments has been neither common nor straightforward - despite the presence of incentives, regulatory contexts, and ubiquitous practical guidance tools. A diverse set of obstructions, occurring within different spatial, temporal and actor hierarchies, are experienced by practitioners and render the realisation of maximised biodiversity, a rarity. This research aims to illuminate why this is so, and what needs to be changed to rectify the situation. To determine meaningful findings and conclusions, capable of assisting applied contexts and accommodating a diverse range of influences, a ‘systems approach’ was adopted. This approach led to the use of a multi-strategy research methodology, to identify the key obstructions and solutions to protecting and enhancing biodiversity - incorporating the following methods: action research, a questionnaire to local government ecologists, interviews and personal communications with leading players, and literature reviews. Nevertheless, ‘case studies’ are the predominant research method, the focus being a ‘nested’ case study looking at strategic issues of the largest regeneration area in Europe ‘the Thames Gateway’, and the largest individual mixeduse mega-development in the UK (at the time of planning consent) ‘Eastern Quarry 2’ - set within the Gateway. A further key case study, focussing on the Central Riverside development in Sheffield, identifies the merits of competition and partnership. The nested cases, theories and findings show that the strategic scale - generally relating to governance and prioritisation - impacts heavily upon individual development sites. It also enables the identification of various processes, mechanisms and issues at play on the individual development sites, which primarily relate to project management, planning processes, skills and transdisciplinary working, innovative urban biodiversity design capabilities, incentives, organisational cultures, and socio-ecological resilience. From these findings a way forward is mapped, spanning aspects from strategic governance to detailed project management.

The link between HR practices, psychological contract fulfillment, and organizational performance:the case of the Greek services sector

The purpose of this study is to investigate the impact of human resource (HR) practices on organizational performance through the mediating role of psychological contract (expressed by the influence of employer on employee promises fulfillment through employee attitudes). The study is based on a national sample of 78 organizations from the public and private services sector in Greece, including education, health, and banking, and on data obtained from 348 employees. The statistical method employed is structural equation modeling, via LISREL and bootstrapping estimation. The findings of the study suggest that employee incentives, performance appraisal, and employee promotion are three major HR practices that must be extensively employed. Furthermore, the study suggests that the organization must primarily keep its promises about a pleasant and safe working environment, respectful treatment, and feedback for performance, in order for employees to largely keep their own promises about showing loyalty to the organization, maintaining high levels of attendance, and upholding company reputation. Additionally, the study argues that the employee attitudes of motivation, satisfaction, and commitment constitute the nested epicenter mediating construct in both the HR practices–performance and employer–employee promise fulfillment relationships, resulting in superior organizational performance. © 2012 Wiley Periodicals, Inc.

Two-dimensional viscoelastic discrete triangular system with negative-stiffness components

Potential applications of high-damping and high-stiffness composites have motivated extensive research on the effects of negative-stiffness inclusions on the overall properties of composites. Recent theoretical advances have been based on the Hashin-Shtrikman composite models, one-dimensional discrete viscoelastic systems and a two-dimensional nested triangular viscoelastic network. In this paper, we further analyze the two-dimensional triangular structure containing pre-selected negative-stiffness components to study its underlying deformation mechanisms and stability. Major new findings are structure-deformation evolution with respect to the magnitude of negative stiffness under shear loading and the phenomena related to dissipation-induced destabilization and inertia-induced stabilization, according to Lyapunov stability analysis. The evolution shows strong correlations between stiffness anomalies and deformation modes. Our stability results reveal that stable damping peaks, i.e. stably extreme effective damping properties, are achievable under hydrostatic loading when the inertia is greater than a critical value. Moreover, destabilization induced by elemental damping is observed with the critical inertia. Regardless of elemental damping, when the inertia is less than the critical value, a weaker system instability is identified.

Anomalies in stiffness and damping of a 2D discrete viscoelastic system due to negative stiffness components

The recent development of using negative stiffness inclusions to achieve extreme overall stiffness and mechanical damping of composite materials reveals a new avenue for constructing high performance materials. One of the negative stiffness sources can be obtained from phase transforming materials in the vicinity of their phase transition, as suggested by the Landau theory. To understand the underlying mechanism from a microscopic viewpoint, we theoretically analyze a 2D, nested triangular lattice cell with pre-chosen elements containing negative stiffness to demonstrate anomalies in overall stiffness and damping. Combining with current knowledge from continuum models, based on the composite theory, such as the Voigt, Reuss, and Hashin-Shtrikman model, we further explore the stability of the system with Lyapunov's indirect stability theorem. The evolution of the microstructure in terms of the discrete system is discussed. A potential application of the results presented here is to develop special thin films with unusual in-plane mechanical properties. © 2006 Elsevier B.V. All rights reserved.