Tamer Aksoy

This study aimed to examine the impact of the internal control system (ICS) on the performance of publicly traded Ghanaian commercial banks, within the context of the core components of the COSO integrated ICS. Accordingly, the study investigated employees' perceptions of the impact of the ICS components on financial performance-FP and non-financial performance-NFP and whether a significant relationship exists between these perceptions. In the study, the core components of the COSO’s ICS (control environment, risk assessment, control activities, information-communication, monitoring) were considered as independent variables, while FP and NFP of the banks were considered as the dependent variables. In line with the study's objective, the hypotheses were designed as follows: H1: The ICS has an impact on the FP. H2: The ICS has an impact on the NFP. Methodologically, a descriptive online survey method was used to collect data. The survey was sent to 113 managers and employees working in the internal control and audit departments of 23 listed Ghanaian banks, and 73 employees, representing 64.6%, provided voluntary feedback. Data were analyzed using SPSS-25. The survey, which was suitable for a 5-point Likert scale, included statements regarding COSO internal control components and FP and NFP. The study revealed that there were no differences in FP among the ICSs but there were differences in NFP among the ICS. The study concluded a statistically significant relationship between the ICS and FP overall. Additionally, compared to other components whose impact on FP was limited, the COSO Information-Communication component indicated the highest significant relationship with FP and the greatest positive impact, while the control activities component had an inverse effect on FP. Furthermore, the study also revealed a significant overall relationship between the ICS and NFP. In addition, compared to other components whose impact on NFP was much more limited, the COSO Information-Communication component showed the highest significant relationship with NFP and the highest positive impact on NFP. This study is considered to contribute to the literature and to investors, shareholders, policymakers, etc., by examining all factors together, such as the impact of COSO internal control components on FP and NFP, and the internal control and audit department staff at the headquarters and branches of listed Ghanaian commercial banks.

Sustainable material selection has become an increasingly important challenge for renewable energy systems because material choices directly influence lifecycle performance, resource efficiency, circularity, and long-term system sustainability. Existing decision-support models generally assume that expert evaluations accurately represent actual preferences, while behavioral biases and hidden cognitive responses are rarely considered. Such limitations may reduce the reliability of strategic decisions for renewable energy planning. This study proposes a novel artificial intelligence-driven decision support framework that integrates biometric facial analysis, Cipher Fuzzy Sets, entropy-based influence propagation, and Choquet synergy analysis to improve expert evaluation reliability under uncertainty. The proposed framework combines explicit linguistic assessments with implicit behavioral information extracted from facial expressions, eye movements, head movements, and facial muscle activity, allowing hidden decision biases to be identified before the final evaluation process. Unlike conventional fuzzy decision models, the proposed approach simultaneously models uncertainty, behavioral inconsistency, and interdependencies among sustainability criteria. The framework is applied to the selection of environmentally sustainable materials for renewable energy systems. The results consistently identify end-of-life recyclability as the most influential criterion across all scenarios, while closed-loop leasing emerges as the most effective material management strategy. The findings demonstrate that reliable material selection for renewable energy systems depends not only on environmental and technical characteristics but also on the quality and consistency of expert judgments. The proposed framework provides a robust computational decision-support tool for renewable energy planning by integrating artificial intelligence, behavioral analytics, and advanced fuzzy modelling under uncertainty.

This study mainly aimed to examine the impact of the COSO’s internal control system components (Control Environment, Risk Assessment, Control Activities, Information-Communication, Monitoring) on corporate governance principles (justice, transparency, accountability and responsibility) through the example of a leading educational foundation in Türkiye. In the study, it was investigated whether there was a significant relationship between the perceptions of employees regarding the effects of the internal control system components on corporate governance. It was also investigated whether these perceptions differed according to demographic characteristics such as gender, age, education, length of service, position. Methodologically, a descriptive online survey method including a questionnaire was applied to collect data. The survey was sent to 234 participants in different departments and positions working in the foundation, and 197 employees responded. The data were analyzed with SPSS-22. The survey, which was suitable for a 5-point Likert scale, included statements regarding demographic characteristics and COSO’s main internal control components and corporate governance principles. The study concluded that all COSO components have a significant and positive relationship with corporate governance principles. In addition, a stronger relationship was revealed between transparency and accountability principles and internal control components compared to others. Furthermore, it was indicated that these perceptions differed according to demographic characteristics. While significant differences were found in perceptions according to demographic characteristics such as gender, age and position, no differences were found according to education and working years criteria. The study is considered to contribute to the literature because it is the first study to examine the impact of the main COSO internal control components on corporate governance principles, together with the example of a leading educational foundation. The study is limited by the selected sample educational foundation, the number of respondents, survey questions-answers, the applied statistical analysis method and tests. Therefore, in order to reach more general results, it is suggested to expand the studies with more diverse and larger numbers of educational foundations, employees, survey questions and statistical methods.

This study mainly aimed to examine the impact of university students' purchasing tendency from e-commerce sites and demographic characteristics on student satisfaction through the example of a leading foundation research university in Türkiye. In the study, it was investigated whether there was a significant difference between students' purchasing tendencies from e-commerce sites and student satisfaction. It was also investigated whether there was a significant difference between demographic characteristics and student satisfaction. Methodologically, a descriptive online survey method including a questionnaire was applied to collect data. The survey was responded by 240 randomly selected students. The data were analyzed with SPSS-26. The study concluded that there was no significant difference between the average daily time spent on the internet and the type of device used to connect to e-commerce sites, which are among the criteria reflecting the tendency to purchase from e-commerce sites, and student satisfaction whereas there was a significant difference between the number of products purchased through e-commerce sites and student satisfaction. Furthermore, it was revealed that there was no significant difference between demographic characteristics such as gender, marital status, education and monthly income and student satisfaction, whereas there was a significant difference between age and student satisfaction. Accordingly, it was indicated that the difference in terms of age was especially in favor of students in the 22-25 age group. It is thought that the study will contribute to the literature by examining the impact of university students' purchasing tendency from e-commerce sites and demographic characteristics on student satisfaction, together with the example of a leading foundation research university. The study is limited by the selected sample foundation research university, the number of students responded, survey questions-answers, the applied statistical analysis methods and tests. Therefore, in order to reach more general results, it is suggested to expand the studies with more diverse and larger numbers of foundation research universities, students, survey questions and statistical methods.

This study mainly aimed to investigate the impact of seasonal changes on media advertising revenues (AR) in R environment through a visual-print media company example. So, the study primarily aimed to examine whether visual, print and internet ARs were affected by seasonal change. The study also aimed to indicate the trends of visual/ print/ and internet ARs over time in the light of seasonality. Furthermore, it was also aimed to make AR estimates for the next year with the best performing methods covering ARIMA and ETS. Methodologically, R programming language and its libraries were used together with ARIMA and ETS time series models. The data set consisted of a monthly ARs series consisting of 180 rows covering the period between January/2007-December/2021 and having a sufficient number of observations for the application of the models. Data were analyzed with R and next year’s forecasts were done with ARIMA and ETS. The study revealed that all AR types were affected by seasonal changes in the specified period and included seasonality, i.e. specially in the summer months. Additionally, it was observed that AR types have different trends despite containing seasonality. The study found that visual ARs denoted a slight downward trend including seasonality during the period. It was also indicated that print ARs reflected a very rapid and drastic downward trend covering seasonality. The study also revealed that internet ARs showed a very rapid and sharp upward trend compared to the other two AR types despite having seasonality. Furthermore, taking into account the calculated error metrics, it was found that the ARIMA model showed the best estimation performance in both i.e. visual and internet ARs. On the other hand, the ETS model indicated the best estimation performance in print ARs. Accordingly, estimations of the visual/print and internet ARs for the next year were made with the best performing methods. It was pointed out that estimated ARs included seasonality in the summer months and revealed similar results to the previous trends based on historical data.

This study mainly aimed to examine the perceptions of Accounting Professionals-APs (Certified Accountant, Certified Public Accountant, Sworn-in Certified Public Accountant) working in Istanbul on accounting culture and fraudulent financial reporting. It also aimed to investigate whether there is a significant relationship between APs’ perceptions of accounting culture and fraudulent financial reporting, and whether these perceptions differ according to demographic characteristics. Methodologically, a descriptive online survey method covering a questionnaire was applied to collect data. The sample consisted of 314 APs operating in Istanbul. Data were analyzed with SPSS-22. The study revealed that there is a significant relationship between the perceptions of APs on accounting culture and fraudulent financial reporting. It also indicated that these perceptions differ according to demographic characteristics. In the light of subvalues of accounting culture, the perceptions of “The Flexibility of Accounting Culture versus Uniformity” and Professionalism versus Status quo” vary according to the gender. In this respect, it was determined that female professionals exhibited more professionalization and uniformity tendencies than men, while male professionals exhibited more flexibility and status quo tendencies compared to women. Furthermore, it was understood that other demographic characteristics (age, years of service, education level, title, number of clients) are not effective variables on the accounting culture perception. On the other hand, it was found that the perceptions of APs on fraudulent financial reporting differ according to demographic characteristics (such as gender, age, years of service and title), however, it does not differ according to the number of customers and education level. In other words, those characteristics do not have any effect on the perception of fraudulent financial reporting.

Çalışmanın amacı, Türkiye'nin önde gelen kurumsal bir yazılı/işitsel/görsel medya şirketi örneği üzerinden medya çalışanlarının hile algısı ve etiğe bakışları ile demografik özellikleri arasında anlamlı bir farklılık olup olmadığını incelemektir. Metodolojik olarak veriler anket yöntemiyle toplandı ve SPSS-22 ile analiz edildi. Anket, farklı departmanları ve pozisyonları yansıtan 202 çalışana uygulandı. Araştırmada katılımcıların yaş, eğitim düzeyi, deneyim yılı, pozisyon gibi demografik özellikleri ile hile algısı ve etiğe bakışları arasında anlamlı bir farklılık olmadığı ortaya çıktı. Ayrıca kadın çalışanların hile algısı ve etiğe bakış açıları ile erkeklerin bakış açıları arasında cinsiyet kriteri açısından önemli farklılıklar olduğu sonucuna varılmıştır. İstatistiksel anlamlılık ve puanlamada, kadınların duyarlılığının erkeklerden daha yüksek olduğu belirlendi. Bir başka deyişle, kadın katılımcıların erkeklere kıyasla hile ve etik değerlere karşı daha duyarlı oldukları ortaya çıktı. Sonuçlar, literatürdeki bazı çalışmalarla da uyumludur. Araştırma 202 çalışanın algılarıyla sınırlı olduğundan, daha genel verilere ulaşmak için daha fazla sayıda farklı medya çalışanıyla çalışmaların yapılması önerilmiştir.

Companies must be able to identify their suppliers appropriately and effectively in order to survive in the competitive market conditions. In order to fulfill and surpass the expectations of the consumers and clients, companies need to interact with the relevant suppliers. It is a tough manner for companies to select the best supplier from a large number of relevant alternatives. The selection process of the appropriate supplier involves multiple interacting and competing factors. Generally, the selection process and its results cause a waste of time and money. For this purpose, MCDM methodologies are utilized to manage this complex process efficiently. MCDMs allows for consistent and accurate decision-making as well as the selection of the most appropriate supplier. MCDM is one the most preferred tool to select the best alternative under the conflicting and competitive criteria when the evaluations are made in crisp numbers. Therefore, MCDM methods are preferred in various applications in academia and real life. However, the evaluations could not be always possible with crisp numbers, especially in vague environments or evaluations needs qualitative data. This study is one of the first to combine the AHP and COPRAS supplier selection methods with interval-valued Pythagorean fuzzy (IPF) logic. The effectiveness of these IPF-AHP and IPF-COPRAS evaluations for the supplier selection problem is compared and examined. The experimental results of case scenarios show that IPF is an effective way to apply in decision-making applications. In addition, sensitivity analysis is conducted to evaluate the proposed methodologies. According to sensitivity analysis, the IPF-AHP and IPF-COPRAS be able to illustrate the effects of small changings in criteria weights. Therefore, companies can use the IPF-AHP and IPF-COPRAS to assist their decision-makers in identifying and selecting the best suppliers.

As a result of the inability of people to meet their demands in the face of increasing demands, people tend to have private health insurance in addition to the general health insurance offered as a public service. Due to the increasing trend of taking out private sustainable health insurance, the number of private sustainable health insurance plans in the health insurance market has increased significantly. Therefore, people may be confronted by a wide range of private health insurance plan options. However, there is limited information about how people analyze private health insurance policies to protect their health in terms of benefit payouts as a result of illness or accident. Thus, the objective of this study is to provide a model to aid people in evaluating various plans and selecting the most appropriate one to provide the best healthcare environment. In this study, a hybrid fuzzy Multiple Criteria Decision Making (MCDM) method is suggested for the selection of health insurance plans. Because of the variety of insurance firms and the uncertainties associated with the various coverages they provide, q-level fuzzy set-based decision-making techniques have been chosen. In this study, the problem of choosing private health insurance was handled by considering a case study of evaluations of five alternative insurance companies made by expert decision makers in line with the determined criteria. After assessments by expert decision makers, policy choices were compared using the Q-Rung Orthopair Fuzzy (Q-ROF) sets Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) and Q-ROF VIšeKriterijumska Optimizacija I Kompromisno Resenje (VIKOR) methods. This is one of the first attempts to solve private health policy selection under imprecise information by applying Q-ROF TOPSIS and Q-ROF VIKOR methods. At the end of the case study, the experimental results are evaluated by sensitivity analysis to determine the robustness and reliability of the obtained results.