The classical Poisson, geometric and negative binomial regression models for count data belong to the family of generalized linear models and are available at the core of the statistics toolbox in the R system for statistical computing. After reviewing the conceptual and computational features of these methods, a new implementation of zero-inflated and hurdle regression models in the functions zeroinfl() and hurdle() from the package pscl is introduced. It re-uses design and functionality of the basic R functions just as the underlying conceptual tools extend the classical models. Both model classes are able to incorporate over-dispersion and excess zeros - two problems that typically occur in count data sets in economics and the social and political sciences - better than their classical counterparts. Using cross-section data on the demand for medical care, it is illustrated how the classical as well as the zero-augmented models can be fitted, inspected and tested in practice. (author's abstract) / Series: Research Report Series / Department of Statistics and Mathematics

The classical Poisson, geometric and negative binomial regression models for count data belong to the family of generalized linear models and are available at the core of the statistics toolbox in the R system for statistical computing. After reviewing the conceptual and computational features of these methods, a new implementation of hurdle and zero-inflated regression models in the functions hurdle() and zeroinfl() from the package pscl is introduced. It re-uses design and functionality of the basic R functions just as the underlying conceptual tools extend the classical models. Both hurdle and zero-inflated model, are able to incorporate over-dispersion and excess zeros-two problems that typically occur in count data sets in economics and the social sciences-better than their classical counterparts. Using cross-section data on the demand for medical care, it is illustrated how the classical as well as the zero-augmented models can be fitted, inspected and tested in practice. (authors' abstract)

Three aspects of complexity in a Production-Marketing System are identified, namely the Model, Decision-Making and Behavioural complexities. Control theoretic and other techniques are reviewed in the context of their contribution to the resolution of these complexities and the modelling and simulation of the PMS is also viewed in this light. Several analytical models of a consumer-durable marketing system are developed, reflecting various assumptions of market conditions ranging from the single-product constant-decision marketing system to the multiproduct variable-decision marketing system, the latter explicitly accounting for price, advertizing, distribution and quality decisions for each product, repeat purchase dynamics and the tastes, income and population of consumers. A production system model is also developed involving a multiple final product, multi-stage production process, permitting the backlogging of demand, variation of production rate by variation in workforce levels and overtime and subcontracting of manufacture of intermediate products. Computer simulatiors of the marketing system based on the models developed and using assumed data are carried out. An optimization routine is used to generate the variable decisions. The variable-decision marketing model is combined with the production model and the resulting limited capacity PMS is simulated using assumed data. The simulation results are presented graphically and attention drawn to their realism. The use of the PMS simulation programme as a nucleus for a comprehensive PMS simulation and control package is commented upon.

In this master thesis we investigated whether it is possible to use automatically generated C code from Function Block Diagram models as an input to the CPAchecker model checker in order to generate automated test cases. Function Block Diagram is a non-executable programming and modeling language. Consequently, we need to transform this language to an executable language that can be model checked. A tool that achieves this is the MITRAC tool, a proprietary development tool used in the embedded system domain, for engineering programmable logic controllers. The purpose of this research was to investigate to what extent the generated C code using MITRAC can be reused as an input to the CPAchecker tool for automated test case generation. In order to achieve this we needed to perform certain transformations steps on the existing code. In addition, necessary instrumentations were needed in order to trigger CPAtiger, an extension of CPAchecker which generates test cases, to achieve maximum condition coverage. We showed that by performing the required modifications it is feasible to reuse the generated C code as an input to CPAchecker tool. We also showed an approach for mapping the generated test cases with the actual Function Block Diagram. We performed mutation analysis in order to evaluate the quality of the generated test cases in terms of the number of injected faults they detect. Test case generation with CPAchecker could be improved in the future in terms of reducing the number of transformations and instrumentations that are currently needed. In order to achieve this we need to add to CPAchecker tool support for structures that are used in C, such as structs. Finally we can extend the type of logic coverage criteria we can use with CPAchecker by adding additional support of FQL language.

This thesis describes a research programme which investigates further the models developed by Conway [1] - the dynamic model of the process of operational research and the life cycle of in-house operational research groups. It studies the relationships between the two, and also extends the range of applicability of the models. From this the research develops a useful tool to assist the strategic management of in-house operational research groups. In the prev ious study, the two mode I s had been re I ated in theory only. This study investigates the actual relationships and develops a method of defining an operational research group's position on its life cycle using data about the mix of proj ects of the dynamic mode I project types. This method was developed using data from the Conway study, and tested on data collected in two surveys conducted during the current period of research. In certain circumstances, it was found to be essential that other aspects of the data on operational research projects were used to help define more exactly the current state of health of the operational research group. The level or importance of the project was shown to be significant, as was the approach employed when tackling the project. The validity of the model with respect to other forms of operational research group was also investigated, and external consultancy was chosen for this research. A classification was developed which categorised consultants according to their managerial structure, and consultants from each of the types in the classification were interviewed using Systems Based Interviewing. The interviews showed that the dynamic model of the process of operational research was a valid way to describe external operational research consultancy. Some preliminary concepts involving the life cycle of consultancies were also developed, but could not be tested within the time scale of this study. 1. CONWAY, D.A., (1984), "The Development and Application of a Dynamic Model of the Process of Operational Research". PhD thesis, Hatfield Polytechnic.

Two important dimensions of work related choices are work location and working hours. Telecommuting (working from home or any convenient place instead of commuting to the conventional working place) can potentially have a substantial impact on traffic demand distribution on a particular day by means of its replacement and displacement effect. Consequently, it is of interest to analyze the effect and extent of telecommuting adoption across the labor force. This study proposes a copula based joint discrete multinomial-duration model of choice accommodating the two dimensions of work related choices: work arrangement and aggregated duration of telecommuting episodes on a particular day. In the econometric model telecommuting episodes are defined so as the duration is at least 30 minutes and only home-based telecommuting is considered and sample is drawn from the ATUS, 2007 data. The results from the estimated model show that gender, higher-education, responsibility for child-care, family ties act as driving forces for adopting telecommuting. The sign of the Gaussian copula parameter or dependency parameter implies that the unobserved factors act in opposite direction on the two dimensions: work arrangement choice and aggregated telecommuting episode duration. / text

在政治學研究中，學者間對「型模」 （model）的討論與使用一直是個富疑義性的主 題，本論文即基此一旨趣，嘗試以方法論的討論為經，政治學研究的實例為緯，分別 就歷史溯源、理論分析與理論綜合的方法，對型模所涉及的諸般問題作一討論。 第一章緒論，簡介本論文研究的動機、目的、範圍與方法。 第二章以歷史溯源的方式，分別探討古典思想中的型模，以及從韋伯理念型以後類型 學的發展，進而論逑其與當代科學哲觀的關係。 第三章討論型模概念的各種界說，包括其與相關概念間的澄清，以及各種分類的觀點 。 第四章從發現的脈胳出發，分別就隱喻、類比、實體的抽象、概念與附號的組合等各 種角度來探究研究者如何去塑造他的型模。 第五章探究型模建構者從何種特殊的觀點來透視他們所關注的政治現象，這些透視包 括時間取向、分析層次、觀點取向以及價值取向等觀點。 第六章討論型模的功能與限制。 第七章結論檢討本論文的若干缺點，以及可能繼續研究的方向。

No description available.

No description available.

No description available.