Papers by Szabolcs Sebrek
Hungarian Statistical Review, 2021
In many applications of linear programming, the lack of exact information results in various prob... more In many applications of linear programming, the lack of exact information results in various problems. Nevertheless, these types of problems can be handled using fuzzy linear programming. This study aims to compare different ranking functions for solving fuzzy linear programming problems in which the coefficients of the objective function (the cost vector) are fuzzy numbers. A numerical example is introduced from the field of tourism and then solved using five ranking functions. Computations were carried out using the FuzzyLP package implemented in the statistical software R.
The Determintants of Strategic Choice Over Openness
Research Papers in Economics, 2014
This paper seeks to explore the drivers of the rate of openness in firms’ innovation processes. T... more This paper seeks to explore the drivers of the rate of openness in firms’ innovation processes. The study aims to underscore the role played by scale economies, the innovativeness of product portfolio, the existence of financial slack, and the rate of internal change in operations. We find that competitive pressure due to economies of scale and possession of financial slack encourage firms to pursue a more open innovation strategy, while a valuable product portfolio embedding superior technologies and the rate of commitment toward internal process changes make firms refrain from being open innovators. To better address the choice toward openness, we apply a more fine-grained measure as distinguishing three types of innovation strategies: open, semi-open, and the traditional closed model. For our empirical analysis, we take data from the 2008 PITEC database, which is the Spanish correspondence of the Community Innovation Survey, and apply a sample of 2148 firms. The econometric model...
Traceability can be studied from different viewpoints. In this paper, we analyze it as a manageme... more Traceability can be studied from different viewpoints. In this paper, we analyze it as a management tool whose implementation implies organizational changes for the firm, but via which improved competitiveness may be realized. More specifically, the aim of this paper is to analyze the evolution of traceability management topic over the past twenty years (1994-2014) through a literature review, to identify the related concepts and settings that have been considered, and further, to delineate possible research gaps in the literature. To achieve this objective we created a self-assembled database, which permitted us to carry out a descriptive analysis of papers and to derive relevant conclusions and different implications for the future. We found that the concept of traceability as a tool to improve organizational performance has gained legitimacy and consequently is now widespread. Hence, traceability is treated from different areas of the firm embracing implementation, control, infor...
Hungarian Statistical Review, 2019
LMMs (linear mixed models) extend simple linear models to allow for both fixed and random effects... more LMMs (linear mixed models) extend simple linear models to allow for both fixed and random effects. Specifically, if an LMM contains only one random effect, the resulting model is a nested error model. Suitable data for a mixed-model analysis can be organised into different levels or clusters, also called 'multilevel' or 'hierarchical' structures. Under this framework, observations within a cluster or group are typically assumed as dependent, while the clusters themselves are assumed as independent from one another (Gurka-Lloyd [2007]). Several methods exist for fitting LMMs, such as the ML (maximum likelihood), REML (restricted maximum likelihood), or moment methods (e.g. McCulloch-Searle [2001], Jiang [1996]). However, these approaches can be seriously affected by the presence of unusual observations in the data or 'outliers'-that might appear as measurement errors, random effects, or both (Fellner [1986], Stahel-Welsh [1997], Sinha-Rao [2009]). A small branch of literature has also focused on the problem with the robust estimation of variance components (e.g.
International Journal of Procurement Management, 2019
This paper shows the evolution of traceability management from 1990-2017 using 124 articles. It l... more This paper shows the evolution of traceability management from 1990-2017 using 124 articles. It lists 73 journals by name, classified in 12 fields of science. We find a dominance of food journals, with journals in supply chain management and IT in a stable second and third position. Articles are coded for nine possible topics and divided into two categories: theoretical and empirical. An increasing Berry index for the nine topics shows an increased dispersion across the various topics. Out of the 43 case studies, 36 relate to the food industry, although more recent publications also deal with other sectors. Various relevant theories are discussed and observed bottlenecks are discussed as well as future potential, like using systems thinking with big data analysis as an enabler.
Acta Oeconomica, 2015
This paper seeks to illuminate empirically a class of drivers of firm performance hitherto neglec... more This paper seeks to illuminate empirically a class of drivers of firm performance hitherto neglected in the economic literature. To accomplish this objective, we distinguished three elements: sales volume, participation in technology alliancing, and successful patent issuing. Our findings suggest that competitive pressure posed by larger rivals in an industry affects sales performance negatively, but the possession of absorptive capacity can counter this deleterious effect. Findings regarding the effects caused by a product portfolio with high technological content are mixed. Depending on the performance measure applied, the results show evidence of adverse outcomes for sales, U-shaped effects for participation in technology alliancing and inverted U-shaped results for patenting. We obtained our raw data from the 2006 and 2008 PITEC database, which is the Spanish equivalent of the EU Community Innovation Survey. Our sample embraces more than 3000 firms.
Sustainability
This paper addresses the phenomenon of overtourism in Budapest from multiple perspectives, starti... more This paper addresses the phenomenon of overtourism in Budapest from multiple perspectives, starting with an overview that uses information collected from news, media, and academic tourism literature. Further, the phenomenon of overtourism is addressed quantitatively using different indicators, including tourism density and intensity. According to these indicators, the center of Budapest (formed by districts I, V, VI, VII, VIII, and IX) has been strongly affected by the presence of tourists, while districts physically far from the center have been less affected. This fact suggests the heterogeneity of the city in terms of overtourism. The number one catalyst of the negative impacts of foreign visitors’ behavior is party tourism (‘ruin pub’ tourism), which involves an unconventional use of the Hungarian capital. Finally, using an unconventional optimization method called fuzzy linear programming, we attempt to explore the challenging problem of identifying the optimal number of touris...
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Papers by Szabolcs Sebrek