INTRODUCING EVOLUTIONARY ANALYSIS TO RETAIL ASSORTMENT PLANNING

Charalampos Saridakis,Stelios Tsafarakis,George Baltas 글로벌지식마케팅경영학회 2014 Global Marketing Conference Vol.2014 No.10

One of the basic strategic decisions a retailer must make involves the determination of the assortment to offer. Product assortment planning (PAP) involves important decisions related to the determination of variety (i.e., number of categories), depth (i.e., number of stock-keeping units within a category) and service level (i.e., amount of merchandise inventory within a category) in a retailer’s product portfolio (Mantrala et al., 2009; Hübner & Kuhn, 2012). By making optimal PAP decisions, retailers hope to satisfy customers’ needs by providing the right service in the right store at the right time (Nogales & Suarez, 2005). Despite the importance of PAP, several limitations and gaps can be found in existing literature. First, existing research tends to examine analytical solutions that deal almost exclusively with questions of depth, whilst it completely fails to address issues related to variety and service levels (see for example, Mantrala et al., 2009). Second, current literature focuses on a single category of products or services and fails to examine the interplay among various categories that are offered by a retailer. Third, although in reality a retailer might have a different assortment at each store format, the academic literature has focused on determining a single assortment for a retailer, which could be viewed as either a common assortment to be carried at all stores or the solution to the PAP problem for a single store (Kök et al., 2006). Finally, Private Labels (PLs) have been widely neglected in existing PAP literature, despite the fact that retailers consider PLs as a powerful competitive tool (Nogales & Suarez, 2005). This paper corrects for omissions of existing PAP research by introducing a new innovative method, namely Differential Evolution (DE). More specifically, the proposed mechanism facilitates simultaneously, strategic PAP decisions, related to the determination of a) optimal variety of PL categories in a retail grocery store, b) optimal service level of PL merchandise within each category, and hence, c) optimal balance between PLs and National Brands (NBs) in a retailer’s product portfolio. The interrelated issue of assortment adaptation across different store formats is also considered. Differential Evolution (DE) is an evolutionary, population-based algorithm, for global optimization over continuous spaces. It was first introduced by Storn and Price (1997), and has been extensively applied to a wide domain of optimization problems due to its ability to efficiently handle non-differentiable, nonlinear and multimodal cost functions. DE is based on the Darwinian theory of Evolution (Engelbrecht, 2007). In a world with limited resources and stable populations, each individual competes with others for survival. The individuals with the best characteristics will more probably survive and reproduce. Those desirable characteristics (a) are passed on to their offspring, (b) are inherited by the subsequent generations, and (c) over time will become dominant among the population. During the production process of a child organism, random events may cause random changes to its characteristics. If these altered characteristics benefit the organism, then the likelihood of survival for the organism is increased. In accordance to this, DE works with a group (population) of candidate solutions to the problem (individuals). The algorithm searches for the global optimum through an iterative process. In each algorithm’s iteration the individuals produce offspring through crossover, and some individual’s characteristics are randomly altered through mutation. The strongest (fittest) individuals of the new population survive to the next generation. Our proposed mechanism is implemented to empirical data that have been collected for the purposes of a large-scale telephone survey research examining consumer buying behaviour in the grocery market of a European metropolitan area. A highly structured questionnaire was developed and data were collected from a random sample of 1,928 supermarket customers. The telephone survey was conducted by the Computer Assisted Telephone Interviewing (CATI) facilities of a local university. In total, we examined consumer preferences for a set of twelve product categories that are usually available in a typical supermarket. We implement our DE algorithm to find optimal solutions (i.e., PL service level per category) in the entire dataset and for three store-formats separately (i.e., large supermarkets, discount supermarkets, small local supermarkets). The derived optimal solution for the entire dataset suggests that retailers should mainly focus their efforts on providing extensive PL service levels in product categories such as disposable paper products and packaged foods, and also maintain a decent PL presence in categories such as bakery, laundry, household cleaning products, tea-coffee, and non-alcoholic beverages. On the other hand, the introduction of PLs in categories such as frozen foods, personal hygiene products and clothing products would not be advisable. Regarding the adaptation of PL service levels across store formats, interesting conclusions can be drawn. For example, managers of large mainstream supermarket chains must offer extensive PL service levels in categories such as disposable paper products and packaged foods, whilst they should maintain a decent PL presence in categories such as laundry and dairy products. In line with our expectations, discount retailers are expected to provide broader varieties of PLs, because in addition to the PL categories offered by mainstream supermarkets, discounters must also provide extensive PL service levels in household cleaning products. It is suggested that discounters not only must offer broader varieties of PLs, but also more extensive service levels within those varieties. Finally, the derived optimal PL service levels in most product categories of local supermarket chains are

INTRODUCING EVOLUTIONARY ANALYSIS TO RETAIL ASSORTMENT PLANNING

Charalampos Saridakis,Stelios Tsafarakis,George Baltas 글로벌지식마케팅경영학회 2014 Global Marketing Conference Vol.2014 No.7

One of the basic strategic decisions a retailer must make involves the determination of the assortment to offer. Product assortment planning (PAP) involves important decisions related to the determination of variety (i.e., number of categories), depth (i.e., number of stock-keeping units within a category) and service level (i.e., amount of merchandise inventory within a category) in a retailer’s product portfolio (Mantrala et al., 2009; H?bner & Kuhn, 2012). By making optimal PAP decisions, retailers hope to satisfy customers’ needs by providing the right service in the right store at the right time (Nogales & Suarez, 2005). Despite the importance of PAP, several limitations and gaps can be found in existing literature. First, existing research tends to examine analytical solutions that deal almost exclusively with questions of depth, whilst it completely fails to address issues related to variety and service levels (see for example, Mantrala et al., 2009). Second, current literature focuses on a single category of products or services and fails to examine the interplay among various categories that are offered by a retailer. Third, although in reality a retailer might have a different assortment at each store format, the academic literature has focused on determining a single assortment for a retailer, which could be viewed as either a common assortment to be carried at all stores or the solution to the PAP problem for a single store (K?k et al., 2006). Finally, Private Labels (PLs) have been widely neglected in existing PAP literature, despite the fact that retailers consider PLs as a powerful competitive tool (Nogales & Suarez, 2005). This paper corrects for omissions of existing PAP research by introducing a new innovative method, namely Differential Evolution (DE). More specifically, the proposed mechanism facilitates simultaneously, strategic PAP decisions, related to the determination of a) optimal variety of PL categories in a retail grocery store, b) optimal service level of PL merchandise within each category, and hence, c) optimal balance between PLs and National Brands (NBs) in a retailer’s product portfolio. The interrelated issue of assortment adaptation across different store formats is also considered. Differential Evolution (DE) is an evolutionary, population-based algorithm, for global optimization over continuous spaces. It was first introduced by Storn and Price (1997), and has been extensively applied to a wide domain of optimization problems due to its ability to efficiently handle non-differentiable, nonlinear and multimodal cost functions. DE is based on the Darwinian theory of Evolution (Engelbrecht, 2007). In a world with limited resources and stable populations, each individual competes with others for survival. The individuals with the best characteristics will more probably survive and reproduce. Those desirable characteristics (a) are passed on to their offspring, (b) are inherited by the subsequent generations, and (c) over time will become dominant among the population. During the production process of a child organism, random events may cause random changes to its characteristics. If these altered characteristics benefit the organism, then the likelihood of survival for the organism is increased. In accordance to this, DE works with a group (population) of candidate solutions to the problem (individuals). The algorithm searches for the global optimum through an iterative process. In each algorithm’s iteration the individuals produce offspring through crossover, and some individual’s characteristics are randomly altered through mutation. The strongest (fittest) individuals of the new population survive to the next generation. Our proposed mechanism is implemented to empirical data that have been collected for the purposes of a large-scale telephone survey research examining consumer buying behaviour in the grocery market of a European metropolitan area. A highly structured questionnaire was developed and data were collected from a random sample of 1,928 supermarket customers. The telephone survey was conducted by the Computer Assisted Telephone Interviewing (CATI) facilities of a local university. In total, we examined consumer preferences for a set of twelve product categories that are usually available in a typical supermarket. We implement our DE algorithm to find optimal solutions (i.e., PL service level per category) in the entire dataset and for three store-formats separately (i.e., large supermarkets, discount supermarkets, small local supermarkets). The derived optimal solution for the entire dataset suggests that retailers should mainly focus their efforts on providing extensive PL service levels in product categories such as disposable paper products and packaged foods, and also maintain a decent PL presence in categories such as bakery, laundry, household cleaning products, tea-coffee, and non-alcoholic beverages. On the other hand, the introduction of PLs in categories such as frozen foods, personal hygiene products and clothing products would not be advisable. Regarding the adaptation of PL service levels across store formats, interesting conclusions can be drawn. For example, managers of large mainstream supermarket chains must offer extensive PL service levels in categories such as disposable paper products and packaged foods, whilst they should maintain a decent PL presence in categories such as laundry and dairy products. In line with our expectations, discount retailers are expected to provide broader varieties of PLs, because in addition to the PL categories offered by mainstream supermarkets, discounters must also provide extensive PL service levels in household cleaning products. It is suggested that discounters not only must offer broader varieties of PLs, but also more extensive service levels within those varieties. Finally, the derived optimal PL service levels in most product categories of local supermarket chains are extremely low. This finding indicates that local grocery stores should concentrate their efforts in providing a narrow variety of PLs, by focusing on few categories, such as packaged food and laundry products. In the light of the entire discussion, we suggest that evolutionary analysis can reveal exciting opportunities not merely for new research, but for novel, revolutionary views of market behavior.

AN ARTIFICIAL NEURAL NETWORKS APPROACH FOR THE IDENTIFICATION OF CAUSAL PATHWAYS TO LOYALTY IN THE AUTOMOBILE MARKET

Charalampos Saridakis,Stelios Tsafarakis,George Baltas 글로벌지식마케팅경영학회 2016 Global Marketing Conference Vol.2016 No.7

The car market is a high-involvement, high-information market, in which consumers are expected to go through extensive searches. Cars are highly symbolic artefacts. The marque and model say a lot about the owner, and evidently, a car is far beyond a purely rational, functionally based purchase. However, car manufacturers face a serious problem as worldwide marque loyalty levels, from purchase to purchase, average below 50%, and tend to decline over time. Evidently, the analysis of factors affecting car marque loyalty is a research topic of significant managerial importance. This study attempts to empirically address the structure of marque loyalty in the car market and has a dual objective: First, to relate marque loyalty to a set of consumer characteristics under a theoretical framework, and second, to examine the impact of current car’s attribute-level performance on loyalty. In this direction, this study illustrates the value of Adaptive Network-based Fuzzy Inference System (ANFIS), as a bridge between qualitative and quantitative approaches, in an attempt to identify alternative complex antecedent conditions that give rise to marque loyalty in the car market. The proposed approach offers to conventional correlational quantitative approaches three benefits: (1) asymmetry (i.e., relationships between independent and dependent variables are treated as non-linear/asymmetric), (2) equifinality (i.e., multiple pathways may lead to the same outcome), and (3) causal complexity (i.e., combinations of antecedent conditions lead to the outcome, and hence, the focus is not on net-effects, but on combinatorial-synergistic effects). To demonstrate these merits, ANFIS is compared to a conventional econometric forecasting technique, namely logistic regression.

Design, synthesis and biological evaluation of novel hydroxamic acids bearing artemisinin skeleton

Ha, V.T.,Kien, V.T.,Binh, L.H.,Tien, V.D.,My, N.T.T.,Nam, N.H.,Baltas, M.,Hahn, H.,Han, B.W.,Thao, D.T.,Vu, T.K. Academic Press ; Academic Press 2016 Bioorganic chemistry Vol.66 No.-

<P>A series of novel hydroxamic acids bearing artemisinin skeleton was designed and synthesized. Some compounds in this series exhibited moderate inhibition against the whole cell HDAC enzymes. Especially, compound 6g displayed potent cytotoxicity against three human cancer cell lines, including HepG2 (liver cancer), MCF-7 ( breast cancer) and HL-60 (leukemia cancer), with IC50 values of 2.50, 2.62 and 1.28 mu g/mL, respectively. Docking studies performed with two potent compounds 6a and 6g using Autodock Vina showed that both compounds bound to HDAC2 with relatively high binding affinities from -7.1 to 7.0 kcal/mol compared to SAHA (-7.4 kcal/mol). It was found in this research that most of the target compounds seemed to be more cytotoxic toward blood cancer cells (HL-60) than liver (HepG2), and breast (MCF-7) cancer cells. (C) 2016 Elsevier Inc. All rights reserved.</P>

A new outlook on membrane enhancement with nanoparticles: The alternative of ZnO

Balta, S.,Sotto, A.,Luis, P.,Benea, L.,Van der Bruggen, B.,Kim, J. Elsevier Scientific Pub. Co 2012 Journal of membrane science Vol.389 No.-

Although several studies explored the use of nanoparticles as additives in membrane structures, mixed matrix membranes still suffer from difficulties in synthesis and applications. In this paper, a new outlook on enhancement of membranes with nanoparticles is proposed by using ZnO as an alternative to TiO<SUB>2</SUB>. Although ZnO has attractive features that potentially could fill the objectives of mixed matrix membranes with lower cost and better performance, challenges in development remain. This paper investigates the synthesis of ZnO enhanced membranes and evaluates the performance of mixed matrix membranes with ZnO nanoparticles. Polyethersulfone (PES) membranes manufactured by diffusion induced phase inversion in N-methyl-pyrrolidone (NMP) using a range of procedures were blended with ZnO nanoparticles in a wide range of concentrations from ultralow to high (0.035-4wt%). It was shown that the new membrane materials embedded with ZnO nanoparticles have significantly improved membrane features. The influence of the ZnO nanoparticles on the characteristics of PES/ZnO membranes was investigated with microscopic observations, contact angle measurement, filtration experiments, fouling resistance determination and observation of the rejection of selected dyes. The results showed an overall improvement compared to the neat membranes in terms of permeability as well as dye rejection and fouling resistance by adding ZnO nanoparticles even in small and ultralow concentrations.

Neutrophil-to-Lymphocyte Ratio in Prognosis of Gastric Cancer

Balta, Sevket,Unlu, Murat,Arslan, Zekeriya,Demirkol, Sait The Korean Gastric Cancer Association 2013 Journal of gastric cancer Vol.13 No.3

The Potential Role of Human Papillomavirus in Colorectal Carcinoma

Balta, Ahmet Ziya,Berber, Ufuk,Tanoglu, Alpaslan,Ozdemir, Yavuz,Demirel, Dilaver Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.10

Can C-Reactive Protein-Lymphocyte Ratio Be Used as a Screening Tool to Confirm the Diagnosis of Periprosthetic Joint Infection?

Orhan Balta,Sezer Astan,Harun Altınayak,Cihan Uçar,Feyza Yildiz Aytekin,Recep Kurnaz 대한정형외과학회 2023 Clinics in Orthopedic Surgery Vol.15 No.6

Background: This study aimed to investigate whether periprosthetic joint infection (PJI) can be predicted by the C-reactive protein-to-lymphocyte ratio (CLR), whether this ratio increases the accuracy of PJI diagnosis, and whether it is more sensitive than other blood values and ratios. Methods: The patients were divided into two groups: the septic revision (SR) group and the aseptic revision (AR) group. In cases of septic revision, the diagnosis of PJI was made based on the criteria proposed by the European Bone and Joint Infection Society (EBJIS). The groups were compared in terms of age, sex, body mass index, comorbidity, and preoperative laboratory results. The sensitivity, specificity, and diagnostic performance of the values and ratios were analyzed and compared. Results: The receiver operating characteristic (ROC) analysis for the CLR gave a diagnostic value of 15.52, which provided a sensitivity of 91.1% and a specificity of 64.2% for PJI. The CLR gave lower specificity and higher sensitivity compared to the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) values. The ROC analysis showed that the CLR had a similar area under the curve (AUC) with the ESR and CRP (0.808). The CLR had a higher specificity than other ratios (platelet volume ratio, neutrophil-tolymphocyte ratio, platelet-to-lymphocyte ratio, and monocyte-to-lymphocyte ratio) and a higher value of the AUC. In the multivariate analysis, the CLR (hazard ratio, 1.088; 95% confidence interval, 1.063–1.113; p < 0.001) was found to be a significant risk factor. As CLR increased by one unit, the risk of PJI increased by 1.088 times, and it was statistically significant (p < 0.001). Conclusions: The findings of this study suggest that CLR can serve as a valuable screening tool for diagnosing PJI. CLR demonstrated higher sensitivity in predicting PJI compared to ESR and CRP, and it exhibited greater specificity than other infection markers.

Neutrophil to Lymphocyte Ratio May Predict Mortality in Breast Cancer Patients

Sevket Balta,Sait Demirkol,Hakan Sarlak,Omer Kurt,Ugur Kucuk,Zekeriya Arslan 한국유방암학회 2013 Journal of breast cancer Vol.16 No.3

Reliability of Fossae Lumbales Laterales and Pelvic Incidence for Estimating Transsacral Corridors Assessed Using Reconstruction Computed Tomography

Orhan Balta,Mehmet Akif Yılmaz,Kürşad Aytekin,Recep Kurnaz,Harun Altinayak,Mehmet Burtaç Eren,Eyüp Çağatay Zengin 대한정형외과학회 2022 Clinics in Orthopedic Surgery Vol.14 No.3

Background: The present study aimed to evaluate the effect of fossae lumbales laterales and pelvic incidence (PI) on transsacral corridors. Methods: Patients who underwent pelvic computed tomography (CT) during routine therapy in a single center between 2015 and 2020 were retrospectively reviewed. The patients’ age and sex were documented during CT examination. Measurements were performed for both the upper and second sacral segments. Height and weight of the patients were determined using appropriate tools and body mass index (BMI) was calculated. Transsacral corridors were identified in true coronal and true sagittal planes and their width was determined as the maximum gap measured so that no screws could come out of the transacral corridors. PI was measured. Results: Our study included 244 (57%) male and 184 (43%) female patients, who had a mean age of 49.3 ± 14.15 years (range, 18–89 years) and a mean BMI of 26.57 ± 2.38 kg/m2. No statistically significant correlation was found between the detection of the dimple sign in physical examination and the presence of an adequate corridor. The PI was statistically significantly higher in the patients with dimples (p < 0.001). PI of the female patients was higher than that of the male patients (p = 0.026). The correlation between PI and the existence of adequate corridors for S1 and S2 screws was not statistically significant (p = 0.858 and p = 0.129, respectively). On the relationship between the presence of adequate S1 and S2 corridors where transsacral screws could be sent, an inverse relationship was detected: if the S1 transsacral corridor was adequate, the S2 corridor was inadequate or vice versa. Conclusions: We could not obtain meaningful results on the use of the dimples of Venus or PI instead of CT to evaluate the adequacy of transverse corridors. Nevertheless, we confirmed that an increased PI was associated with the presence of dimples of Venus.