Run length analysis of Shewhart charts applied to drifting processes under an integrative SPC/EPC model

Engineering Process Controllers (EPC) are frequently based on parametrized models. If process conditions change, the parameter estimates used by the controllers may become biased, and the quality characteristics will be affected. To detect such changes it is adequate to use Statistical Process Control (SPC) methods. The run length statistic is commonly used to describe the performance of an SPC chart. This paper develops approximations for the first two moments of the run length distribution of a one-sided Shewhart chart used to detect two types of process changes in a system that is regulated by a given EPC scheme: i) changes in the level parameter; ii) changes in the drift parameter. If the drift parameter shifts, it is further assumed that the form of the drift process changes from a linear trend under white noise (the in-control drift model) into a random walk with drift model. Two different approximations for the run length moments are presented and their accuracy is numerically analyzed. Received: August 1998     

Assessing empirical research on value-based management: Guidelines for improved hypothesis testing

The claims that value-based management (VBM) increases corporate performance have attracted considerable interest among researchers and organizations over the last three decades. Even though many studies have been conducted, the evidence on whether users outperform non-users is inconsistent. This paper attempts to place these diverse findings into perspective, and provide venues for future research. For that purpose, we drafted a framework to analyze 120 empirical studies on VBM. We concluded that meaningful hypothesis tests have been impaired by the narrow scope of data sets as well as methodological misspecifications. Based on this analysis, we categorized studies into four streams of research, employing factor analysis and cluster analysis. We then suggested that the most sophisticated studies identified positive performance effects of VBM. Lastly, we derived guidelines to improve the hypothesis testing of future studies on VBM.     

Attitudes and Preferences of Kosovar Consumer Segments Toward Quality Attributes of Milk and Dairy Products

ABSTRACT

The dairy market is one of the fastest growing agri-food sectors in Kosovo, yet the farm structure is fragmented. The level of productivity is lower compared with European Union levels and shows potential for improvements. The consumption of dairy products is expected to rise due to income growth and segmentation of consumers that would reflect different preferences for low-fat or zero-fat products, products with natural additives, and so on. On the market level, a significant share of the consumed milk and dairy products is imported. This study aims to better understand attitudes and preferences of Kosovar consumer segments toward milk and dairy products. A quantitative survey with 300 consumers was conducted in major Kosovo cities. Applying a reduced version of the Food Related Lifestyle instrument identified three distinct consumer segments: the conservative consumer segment, the socially oriented foodie, and the information-seeking eco-consumer. The latter two segments are especially open to trying new food products and actively search information about food. All three consumer segments show strong consumer patriotism by believing that domestic milk and cheese are safer than imported products and are of higher quality. This indicates the strong market potential for dairy farmers and companies in the Kosovo, which should develop new food products having these segments in mind. The authors explore the strategies that farmers and companies should use to better target these consumer groups and gain greater access to desirable segments.     

The Effect of Implicit Moral Attitudes on Managerial Decision-Making: An Implicit Social Cognition Approach

This article concerns itself with the relationship between implicit moral cognitions and decisions in the realm of business ethics. Traditionally, business ethics research emphasized the effects of overt or␣explicit attitudes on ethical decision-making and neglected intuitive or implicit attitudes. Therefore, based on an implicit social cognition approach it is important to␣know whether implicit moral attitudes may have a substantial impact on managerial ethical decision-making processes. To test this thesis, a study with 50 participants was conducted. In this study the participants were asked to work on a deliberative managerial ethical decision-making task, in which they had to decide on one of two options. Implicit moral attitudes towards the two options were measured using the implicit association test (IAT). A semantic differential scale was used to diagnose explicit moral attitudes towards the two options. Each step taken within the deliberative decision-making process, as well the decision itself, was assessed using a scoring model-based decision analysis and a decision-making questionnaire. The results of this study show that implicit moral attitude has a great influence on the deliberative ethical decision-making process. The derived conclusion is that complex and deliberative decision-making processes in the context of business ethics can be affected by implicit social cognitions such as implicit moral attitudes.     

The Determinants of GATS Commitment Coverage

This paper investigates hypotheses about the determinants of trade and investment liberalisation with a particular focus on the market access and national treatment commitments under the General Agreement on Trade in Services (GATS). We set up a database of these GATS commitments and use the ratio of all commitments listed by a country to the possible number of commitments as a measure of liberalisation of market access/national treatment. Our empirical analysis suggests that larger and ‘richer’ countries commit to more liberal regimes of market access and national treatment. This is surprising since economic theory predicts the largest welfare gains for low‐skilled abundant (skilled‐labour/physical‐capital‐scarce) economies. Also, our findings suggest that liberalisation is stronger among geographically close countries with strong ties in goods trade.     

Hedging Long-Term Forwards with Short-Term Futures: A Two-Regime Approach

In this paper we investigate Metallgesellschafts problem of hedging long-term forwards with short-term futures. Very different hedging strategies have been proposed in the literature. We attribute these differences to the underlying valuation approaches for oil futures and empirically compare five model-based hedging strategies. In particular, we consider a strategy which results from a two-regime pricing model. This continuous-time equilibrium model reflects the observation that prices of oil futures exhibit a very different behavior for low and high oil prices. Our empirical study shows that time diversification is the dominant effect for an effective hedging of long-term oil forwards with short-term futures. JEL classification G13, G30     

Lean Trees—A General Approach for Improving Performance of Lattice Models for Option Pricing

The well-known binomial and trinomial tree models for option pricing are examined from the point of view of numerical efficiency. Common lattices use a large part of time resources for calculations which are almost irrelevant for the solution. To avoid this waste of resources, the tree is reduced to a lean form which yields the same order of convergence, but with a reduction of numerical effort. In numerical tests it is shown that the proposed method leads to a significant improvement in real calculation time without loss of accuracy for a broad class of derivatives.     

Günstige Aufkommensperspektiven — Steuererhöhungen nicht erforderlich

In May 2013, the Working Party on Tax Revenue Forecasting presented its new estimate, which is based on the federal government’s spring projection of the medium-term development of the overall economy. Tax revenues are estimated to expand from yy600 bn in 2012 to yy704.5 bn in 2017. Because the tax revenues increase at a faster pace than the nominal GDP, the tax-to-GDP ratio increases from 22.7% to 23.1%. Contrary to the diagnosis of the opposition parties in the German Bundestag, we see no structural revenue gap. In fact, public budgets will realise structural surpluses in the coming years if governments are successful in constraining expenditure growth. There are no convincing reasons to increase public revenues by increasing tax rates or launching new fees; in both cases tax burdens would increase and that would dampen economic growth. Instead, there will be budgetary leeway to reduce the fiscal drag if governments are committed to a sound consolidation policy.     

Competences for green development and leapfrogging in newly industrializing countries

Competences for green development and leapfrogging in Newly Industrializing Countries are becoming increasingly urgent from a global perspective. The integration of these innovations into the development process in the rapidly growing economies requires knowledge build-up and technology cooperation. The prospect of exporting sustainability technologies can add an incentive for them to move towards sustainability technologies. These issues also affect innovations to increase material efficiency, which are receiving increasing interest among sustainability innovations. The competences for green development are analyzed with an innovation indicator approach. The general innovation capabilities are evaluated using R&D indicators and survey results about general innovation capabilities. Technological competences in the sustainability fields are a key indicator for the absorptive capacity of sustainability technologies and for the ability to export them. International patents and publications, and successes in foreign trade indicate to what extent a country is already able to participate in global technology markets. The resulting pattern shows various strengths and weaknesses of the analyzed countries. In general, the knowledge build up in material efficiency strategies is above-average in the Newly Industrializing Countries. There is a strong need for strategic positioning of the countries and for coordination of the various policy fields involved.     

Resistant decomposition of economic time series

The paper proposes two resistant methods for time series decomposition, i. e., methods that are insensitive to a few aberrant observations. One is based on running medians instead of the usual moving averages and is designed along the lines of SABL, a package developed shortly after Tukey's ideas were published. The other method uses structural time series models and adapts smoothing splines which are suitably robustified. The resistance of the two methods are studied by employing the concept of the breakdown point. Also resistance and efficiency are investigated by the means of a suitably chosen model.

---

Zusammenfassung Es werden zwei resistente, d. h. gegen Ausreißer unempfindliche Methoden zur Zerlegung von Zeitreihen vorgestellt. Die erste benutzt gleitende Mediane anstelle der üblichen gleitenden Durchschnitte und vereinfacht das Verfahren SABL. SABL wurde als resistentes Zerlegungspaket kurz nach der Publikation von Tukeys Ideen zur explorativen Datenanalyse entwickelt. Die zweite Methode geht von strukturellen Zeitreihenmodellen aus und verwendet verallgemeinerte glättende Splines, die geeignet robustifiziert werden. Die Resistenzeigenschaften der beiden Verfahren werden anhand des Bruchpunkt-Konzeptes sowie auf der Basis eines Modells diskutiert. Zudem dient das Modell als Grundlage zur Einschätzung ihrer Effizienz.

---

---

I am grateful to the referees for several helpful comments and suggestions.