Decision-making experiments on dual sales channel coordination

In this thesis, we conduct an experimental study with human decision makers, on dual sales channel coordination. We aim to determine dual channel strategies for a manufacturer who sells its product thorough both an independent retailer channel and its totally owned direct online channel. The two channels compete on service, where the service level of the retailer channel is measured with its product availability level, and the service level of the direct channel is measured with its delivery lead time. This multi-stage game-theoretical model was previously solved for the wholesale price contract (Chen et al. 2008) and buyback contract (Gökduman and Kaya 2009) cases. We compare these models' theoretical predictions with the outcome of our experiments with human decision makers. In particular, we analyze the theoretical and observed coordination performance of the wholesale price and buyback contracts between the two firms. We identify deviations from theoretical predictions that can be attributed to behavioral factors, such as risk aversion

SURVIVAL ABILITY OF FIRMS: THE CASE OF ISE

Finansal piyasalarda meydana gelen bir krizin reel piyasaları da etkilemesi kaçınılmazdır. Kriz süreçlerinde ve sonrasında şirketlerin hayatta kalabilmeleri, borç yapıları ve faaliyet kararları ile doğrudan ilişkilidir. Bu bakımdan borsada işlem gören şirketlerin borç/özkaynak yapıları ile faaliyet kararları arasındaki uyum, özellikle kriz dönemlerinde şirketlerin hayatta kalma kabiliyetleri açısından oldukça önemlidir. Bu çalışmada da Türkiye'de İMKB Sınai Endeksine kayıtlı 142 şirketin 2007 krizi öncesi ve sonrasında hayatta kalma kabiliyetleri Veri Zarflama Analizi yoluyla incelenmiştir. Analizde ölçeğe göre sabit getiri yaklaşımı kullanılmıştır. Kullanılan girdiler şirketlerin finansal yapılarıyla ilgili olurken, çıktılar şirketlerin faaliyet kararlarıyla ilgilidir. Analiz sonucunda; kriz öncesinde inceleme konusu olan 136 şirketin 18 tanesi göreli etkin olarak tespit edilirken, kriz sonrasında bu sayı 24 olarak tespit edilmiştir. Bu durum İMKB Sınai Endeksine kayıtlı şirketlerin borç yönetimi açısından kırılgan bir yapıya sahip olduklarını göstermektedir. The crisis taking place in the financial markets inevitably affects the reel sector. Survival of the firms during or after the crises is closely related to their debt structures and operational decisions. In this respect, consistency between debt/equity structures and operational decisions of the listed companies is crucial in terms of their survival-ability, particularly during the crisis periods. This paper examines survival ability of the 142 firms registered to the İstanbul Stock Exchange (ISE) Industrial Index both before and after the crisis. Constant returns to scale approach is used in the analysis. While the input variables used are related to the financial structures of the firms, the output variables refer to the operational structures of the firms. Of the 136 firms from the sample whose analyzable data was accessed, 18 are found to be relatively efficient before the crisis. The number of relatively efficient firms rises to 24 after the crisis. This situation leads to a conclusion that the firms registered to ISE Industrial Index are vulnerable in terms of debt management

Machine Learning to Identify Dialysis Patients at High Death Risk.

IntroductionGiven the high mortality rate within the first year of dialysis initiation, an accurate estimation of postdialysis mortality could help patients and clinicians in decision making about initiation of dialysis. We aimed to use machine learning (ML) by incorporating complex information from electronic health records to predict patients at risk for postdialysis short-term mortality.MethodsThis study was carried out on a contemporary cohort of 27,615 US veterans with incident end-stage renal disease (ESRD). We implemented a random forest method on 49 variables obtained before dialysis transition to predict outcomes of 30-, 90-, 180-, and 365-day all-cause mortality after dialysis initiation.ResultsThe mean (±SD) age of our cohort was 68.7 ± 11.2 years, 98.1% of patients were men, 29.4% were African American, and 71.4% were diabetic. The final random forest model provided C-statistics (95% confidence intervals) of 0.7185 (0.6994-0.7377), 0.7446 (0.7346-0.7546), 0.7504 (0.7425-0.7583), and 0.7488 (0.7421-0.7554) for predicting risk of death within the 4 different time windows. The models showed good internal validity and replicated well in patients with various demographic and clinical characteristics and provided similar or better performance compared with other ML algorithms. Results may not be generalizable to non-veterans. Use of predictors available in electronic medical records has limited the assessment of number of predictors.ConclusionWe implemented and ML-based method to accurately predict short-term postdialysis mortality in patients with incident ESRD. Our models could aid patients and clinicians in better decision making about the best course of action in patients approaching ESRD

Temporal and palaeoclimatic context of the evolution of insular woodiness in the Canary Islands

Insular woodiness (IW), referring to the evolutionary transition from herbaceousness toward woodiness on islands, has arisen more than 30 times on the Canary Islands (Atlantic Ocean). One of the IW hypotheses suggests that drought has been a major driver of wood formation, but we do not know in which palaeoclimatic conditions the insular woody lineages originated. Therefore, we provided an updated review on the presence of IW on the Canaries, reviewed the palaeoclimate, and estimated the timing of origin of woodiness of 24 insular woody lineages that represent a large majority of the insular woody species diversity on the Canaries. Our single, broad‐scale dating analysis shows that woodiness in 60%–65% of the insular woody lineages studied originated within the last 3.2 Myr, during which Mediterranean seasonality (yearly summer droughts) became established on the Canaries. Consequently, our results are consistent with palaeoclimatic aridification as a potential driver of woodiness in a considerable proportion of the insular woody Canary Island lineages. However, the observed pattern between insular woodiness and palaeodrought during the last couple of million years could potentially have emerged as a result of the typically young age of the native insular flora, characterized by a high turnover