Browsing by Author "Peker, Sinem"

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Aralık Tip II Genelleştirilmiş Çan Şekilli Bulanık Sayının Aralık Yakınsaması
(2019) SİNEM PEKER; Efendi NASİBOV; Peker, Sinem; Nasibov, Efendi
Üyelik derecelerinin bulanık olduğu durumlarda Tip II bulanık sayıları kullanılır. Ancak bu sayılar bazı yöntemlerde uygulanamayabilir ve bunların yakınsamaları oluşturulmak istenebilir. Bu çalışmada aralık Tip II genelleştirilmiş çan şekilli bulanık sayısının aralık yaklaşımı dikkate alınmış ve özel bir hal için aralığın bilinmeyen parametrelerinin formülleri bulunmuştur.
Beklenen Aralığa Dayanan Aralık Tip II Üssel Bulanık Sayının Aralık Tip II Parametrik Yamuk Bulanık Sayı Yakınsaması
(2021) Efendi Nasibov; Sinem Peker; Nasibov, Efendi; Peker, Sinem
Tip I bulanık sayıları belirsizliği ele almak için bazı karar verme problemlerinde kullanılmaktadır. Tip I bulanık sayılarının üyelik dereceleri adi sayılardır. Ancak gerçek yaşam problemlerinde üyelik derecelerinin bulanık sayılar ile gösterilebileceği olaylar var olabilir. Bu gibi durumlarda Tip II bulanık sayıları kullanılabilir. Bulanık sayının daha basit bir formunun kullanılması bazı çalışmalarda karmaşık hesaplamalardan kaçınmak için bir avantaj olarak görülmektedir. Bu durum dikkate alınarak bu çalışmada aralık Tip II üssel bulanık sayının aralık Tip II parametrik yamuk bulanık sayı yakınsaması beklenen aralıkların eşitliklerinin kullanıldığı bir kısıtlı optimizasyon problemi ile bulunmuş ve formüller verilmiştir.
Bulanık sayıların sıralanması
(2015) Özmen, Ayşegül; Peker, Sinem
Fuzzy numbers are used to express and uncertain results of real life situations. Comparing and ranking fuzzy numbers are major challenges faced in the fuzzy set theory, which is used in many different areas such as artificial intelligence, economical systems, data analysis and decision-making mechanisms. From the first method defined until today, many different methods have been developed for ranking of fuzzy numbers required to calculate and compare different choices. In this study, many different methods are investigated in general terms or their formulas. Also, the similarities as well as the differences between some of the methods are shown by numerical example. Moreover, the fuzzy numbers generated as the group of data, which was provided by scoring the happiness levels of a group of students between 0-100, was transformed into fuzzy number sets were ranked by using some of the methods within the scope of this study and given place in the application part. Keywords: Fuzzy number, Ranking, Fuzzy Set Theory
CLUSTERING IN EUROPEAN STOCK INDICES IN CRISIS AND NON-CRISIS PERIODS
(VILNIUS GEDIMINAS TECHNICAL UNIV PRESS TECHNIKA, 2014) Sinem Peker; Bora Aktan; Peker, Sinem; Aktan, Bora; J Stankeviciene; R Ginevicius; AV Rutkauskas
Grouping the major indices of stock markets based on their homogeneities may facilitate the selection period for investors especially today's information rich financial world. This paper attempts to detect and group the homogenous stock indices in Europe both throughout the crisis and non-crisis periods. The daily index returns of leading stock exchanges over the period 03.01.2007-09.04.2013 are considered, one of the hierarchical clustering techniques so-called Ward's Method is applied and similar cases are evaluated respectively. Then Wilcoxon signed rank test is employed for the same periods on daily index returns and meaningful differences are found.
Citation - WoS: 1
Citation - Scopus: 1
Decision Influence of the Marketing Department in the Organization: An Emerging Country Perspective
(NOMOS VERLAGSGESELLSCHAFT MBH & CO KG, 2018) Osman Gok; Gungor Hacioglu; Sinem Peker; Hacioglu, Gungor; Gok, Osman; Peker, Sinem
The role and influence of the function of marketing within the organization has been the focus of scholarly research and practitioners' attention in the business literature. Despite its central role and locus in business organizations concerns remain about the contributions of marketing and the department has received insufficient acknowledgment from its constituents in the organization. Responding to calls for research in the area this study empirically examines the antecedents of the marketing department's influence and discusses the effects of an influential marketing department on firm performance. Our non-marketer weighted sample considers marketing to be an influential function within the organizations surveyed. The findings reveal that marketing capabilities constitute a critical set of competences for business success but the department's decision influence is not an influential factor for firm performance. The study includes an advanced emerging country perspective on the notion of marketing's influence within business organizations.
Interval Type II Fuzzy Number Generation From Data Set Applied to Sedation Stage Classification
(IGI Global, 2020) Efendi N. Nasibov; Sinem Peker; Nasibov, Efendi; Peker, Sinem
There are several ways to summarize the data.set by using measures of locations dispersions charts and so on. But how can the data set be represented or shown when uncertainty exists in the environment process? Usage of the fuzzy number can be a way to handle the uncertainty in the representation of the data set. This chapter focuses on the membership function construction from the data set and introduces the formulas for the interval Type-2 generalized bell-shaped fuzzy number generation based on the data set. The bispectral index scores (BIS) are processed to see the ability of the offered methods in the construction of the interval Type -2 generalized bell-shaped membership function in the real data set. The obtained membership functions are used for a classification problem of sedation stages according to BIS data sets. Classification accuracies are calculated. © 2022 Elsevier B.V. All rights reserved.
Citation - WoS: 54
Citation - Scopus: 67
On the nearest parametric approximation of a fuzzy number
(ELSEVIER SCIENCE BV, 2008) Efendi N. Nasibov; Sinem Peker; Nasibov, Efendi N.; Peker, Sinem
Many nearest parametric approximation methods of fuzzy sets are proposed in the literature. It is clear that the specific approximations may lead to the loss of information about fuzziness. To overcome this problem most of these methods rely on the minimization of the distance between the original fuzzy set and it approximation But these approximations mostly are not flexible to the decision maker's choice. Hence in this paper we offer a parametric fuzzy approximation method based on the decision maker's strategy as an extension of trapezoidal approximation of a fuzzy number. This method comprises the selection of the form of the parametric membership function and its evaluation. (c) 2007 Elsevier B.V. All rights reserved.
Citation - WoS: 9
SUSTAINABLE RISK MANAGEMENT: FUZZY APPROACH TO VOLATILITY AND APPLICATION ON FTSE 100 INDEX
(ENTERPRENEURSHIP & SUSTAINABILITY CENTER, 2014) Sinem Peker; Manuela Tvaronaviciene; Bora Aktan; Peker, Sinem; Aktan, Bora; Tvaronaviciene, Manuela
In this paper a fuzzy volatility labeling algorithm is offered to detect the periods with abnormal activities on daily share returns. Considering the vagueness in the switches of the time periods the membership functions of high and normal volatility classes are introduced. In the assignments both the density structure and membership degree are used. It is believed that this algorithm may be helpful to construct different estimation models for the time periods with normal and abnormal activities. Authors offer algorithm which can be used as a tool for sustainable risk management.
Citation - WoS: 9
Citation - Scopus: 11
THE IMPACT OF MARKETING'S INNOVATION-RELATED CAPABILITIES ON A FIRM'S INNOVATION PERFORMANCE
(WORLD SCIENTIFIC PUBL CO PTE LTD, 2020) Osman Gok; Sinem Peker; Gok, Osman; Peker, Sinem
Innovation performance is a potential source of competitive advantage for any firm. A capable marketing department (MD) can contribute significantly to the market success of the new products and services offered. Therefore understanding the impact of marketing's innovation-related capabilities in the innovation process is an important area of inquiry to achieve a more innovative and competitive company. This study examines the relations among relevant MD capabilities marketing's decision influence on innovation development and a firm's innovation performance. The results indicate that the capabilities of the MD are strongly associated with the firm's innovation performance. Our findings also demonstrate that marketing capabilities have a positive relationship with the department's influence on innovation development. However the department's influence on innovation decisions has no effect on the firm's innovation performance. We proposed a moderated mediation model considering a set of firm-level and environmental contingency variables. Results reveal that the proposed model relationships are indifferent for all the sub-groups of moderators.
Citation - WoS: 9
Citation - Scopus: 10
The marketing department's reputation in the firm
(ELSEVIER SCI LTD, 2015) Osman Gok; Sinem Peker; Gungor Hacioglu; Hacioglu, Gungor; Gok, Osman; Peker, Sinem
The role effectiveness and credibility of the marketing function within a firm have been the focus of scholarly research and practitioners' attention in marketing and both researchers and practitioners argue that the marketing department's reputation has been besmirched in recent years. This study makes an initial attempt to empirically investigate antecedents and consequences of the marketing department's reputation within the firm. We put forward the notion that the marketing department's reputation is a key factor in the junction of the departmental influence and power-oriented research streams. The results indicate that the customer connection capability accountability and status of the marketing department are positively related to its reputation in the firm. Conversely the variable of the resources controlled by marketing is negatively associated with the department's reputation. The results further show that a reputable marketing department is associated with improved market performance regardless of the generic strategy pursued by the firm. Development of departmental capabilities is vital for marketing to be a respected department in the organization. Marketers also have to build favorable perceptions on and beyond their capabilities within the firm and upper echelons. (C) 2015 Elsevier Ltd. All rights reserved.
Citation - WoS: 5
Citation - Scopus: 4
Time series labeling algorithms based on the K-nearest neighbors' frequencies
(Pergamon-Elsevier Science Ltd, 2011) Efendi N. Nasibov; Sinem Peker; Nasibov, Efendi N.; Peker, Sinem
In the current paper time series labeling task is analyzed and some solution algorithms are presented. In these algorithms fuzzy c-means clustering which is one of the unsupervised learning methods is used to obtain the labels of the time series. Then K-nearest neighborhood (KNN) rule is performed on the labels to obtain more relevant smooth intervals. As an application the handled labeling algorithms are performed on bispectral index (BIS) data which are time series measures of brain activity. Finally smoothing process is found useful in the estimation of sedation stage labels. © 2010 Elsevier Ltd. All rights reserved. © 2011 Elsevier B.V. All rights reserved.
Tip II Genelleştirilmiş Çan Şekilli Bulanık Sayısının Tip II Parametrik Yamuk Bulanık Sayı Yakınsanması
(2019) Efendi Nasibov; Sinem Peker; Nasibov, Efendi; Peker, Sinem
Belirsizliğin olduğu durumlarda bulanık sayının 0 ve 1’den farklı olarak diğer üyelik seviyelerine olanak tanıması çeşitli uygulamalarda bulanık sayının kullanılmasına yol açmıştır. Tip 1 bulanık sayılarda her bir x değerine bir üyelik seviyesi ataması yapılmaktadır. Ancak her bir x değerinin üyelik seviyesine sadece bir üyelik değeri atanmasının zor olduğu durumlar olabilir. Bu gibi durumlarda her bir x değerine bulanık bir sayı şeklinde üyelik derecesi atanmasına olanak tanıyan Tip II bulanık sayıları kullanılabilir. Bulanık sayı işlemlerinde karmaşık tipte bulanık sayılar kullanıldığında bazen zorluklar yaşanabilir ve daha basit yapıdaki bulanık sayılarla çalışılmak istenebilir. Bu çalışmada Tip II genelleştirilmiş çan ve daha basit yapıdaki Tip II parametrik yamuk bulanık sayıları ele alınmış ve Tip II genelleştirilmiş çan bulanık sayısının Tip II parametrik yamuk yakınsaması oluşturulmuştur.
Citation - WoS: 86
Citation - Scopus: 102
Understanding the links among innovation performance market performance and financial performance
(Springer Verlag service@springer.de, 2017) Osman Gök; Sinem Peker; Gök, Osman; Peker, Sinem
Innovation and its impacts on business performance are strategically vital deliberations for modern business organizations. In this study we examine how innovation performance affects two different facets of firm performance: market performance and financial performance. Many studies address the relationship between innovation and business performance but few empirical studies analyze the interplay between those variables. Research results reveal a suppression effect of market performance on the innovation–financial performance relationship. We find a negative direct relationship between innovation and financial performance, however market performance reverses this negative effect to a positive total influence through its suppression effect. This result indicates the vital role of market performance in converting innovation to positive financial outcomes. The proposed mediation model is relevant regardless of the set of firm-level and environmental contingency variables. © 2017 Elsevier B.V. All rights reserved.
Citation - Scopus: 1
What Ward's clustering method tells about the four largest emerging equity markets?
(Inderscience Publishers, 2020) Bora Aktan; Sinem Peker; Makram A. Bellalah; Peker, Sinem; Bellalah, Makram; Aktan, Bora
Investing in stock market indices or ETFs could be more reasonable (and secure) for relatively new and incognisant investors who are personally unable to value of each stock/firm in a way. This paper attempts to group the well-known four largest emerging stock markets so-called BRIC or big-four economies namely Brazil Russia India and China based on return characteristics through Ward's hierarchical clustering method over the period of 2005 and 2015. Additionally the first principle component (PCA) of the related indices is calculated and the abnormal variability is observed through control chart over time. Results indicate that Brazilian and Indian markets show more similarity over the studied period. © 2020 Elsevier B.V. All rights reserved.