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Öğe Characterizations of Geometric and Discrete Pareto Distributions Based on the Conditional Distribution of kth Records(Atlantis Press, 2016) Oncel, Sevgi Yurt; Aliev, FazilThe poblem of characterizing of discrete probability distributions is an important problem. Recently many new results are obtained in characterization of distributions using kth records. Based on the distributional properties of kth weak and ordinary records some characterizations of geometric and discrete pareto distributions are given.Öğe Depression Problems Among Turkish Twins(Elsevier Science Bv, 2019) Aliev, Fazil; Oncel, Sevgi Yurt…Öğe Fagerstrom Test for Nicotine Dependence (FTND) and smoking behavior among Turkish college students(Springer, 2009) Oncel, Sevgi Yurt; Aliev, Fazil; Dick, Danielle; Gebizlioglu, Omer L.…Öğe A note on the characterization of pareto distribution by the hazard rate of upper record values(Isoss Publ, 2013) Ahsanullah, Mohammad; Aliev, Fazil; Oncel, Sevgi YurtLet {X-i, i = 1 2, ... } be a sequence of independent and identically distributed (iid) random variables with absolutely continuous (with respect to Lebesgue measure) cumulative distribution function (cdf) F(x) with F(1) = 0 and the corresponding probability density function (pdf) f(x). We provide two characterizations of Pareto distribution based on ratios of upper records and properties of hazard rate.Öğe Parameter estimation of some Kumaraswamy-G type distributions(Springer Heidelberg, 2017) Arslan, Guvenc; Oncel, Sevgi YurtSince Kum-G distributions have additional two parameters, the estimation of parameters becomes an interesting problem by itself. In this study, we consider parameter estimation of Kum-Weibull, Kum-Pareto and Kum-Power distributions by using the maximum likelihood and the maximum spacing methods. These three distributions are important in reliability and other applications. The Kum-Pareto and Kum-Power distributions have parameterdependent boundaries, which makes the estimation of parameters more interesting. We performed simulations for each of these considered distributions by using the R software for estimating parameters using the maximum likelihood and the maximum spacing method. In addition, an application of these distribution families to real data for modeling wind speed in a particular location in Turkey is discussed.Öğe Risk Factors Influencing Smoking Behavior: A Turkish Twin Study(Cambridge Univ Press, 2014) Oncel, Sevgi Yurt; Dick, Danielle M.; Maes, Hermine H.; Aliev, FazilAim: In this study, we introduce the first twin study in Turkey, focusing on smoking behavior, and laying the foundation to register all twins born in Turkey for research purposes. Using Turkish twins will contribute to our understanding of health problems in the context of cultural differences. Materials and methods: We assessed 309 twin pairs (339 males and 279 females) aged between 15 and 45 years living in the Kirikkale and Ankara regions of Turkey, and administered a health and lifestyle interview that included questions about smoking status and smoking history. We analyzed the data using descriptive statistics, t-tests, chi-square tests, and bivariate and multivariate clustered logistic regression. In addition, we fit bivariate Structural Equation Models (SEM) to determine contributions of latent genetic and environmental factors to smoking outcomes in this sample. Results: One hundred seventy-eight participants (28.8%) were identified as smokers, smoking every day for a month or longer, of whom 79.2% were males and 20.8% were females. Mean values for number of cigarettes per day and the Fagerstrom Test of Nicotine Dependence (FTND; Fagerstrom, 1978) score were higher in males than in females, and age of onset was earlier in males. There was a significant positive correlation between the FTND score and number of cigarettes smoked per day, and a significant negative correlation between both variables and age at onset of smoking. Our study showed that gender, presence of a smoking twin in the family, age, alcohol use, marital status, daily sports activities, and feeling moody all played a significant role in smoking behavior among twins. The twin analysis suggested that 79.5% of the liability to FTND was influenced by genetic factors and 20.5% by unique environment, while familial resemblance for smoking initiation was best explained by common environmental factors. Conclusions: Marked differences in the prevalence of smoking behavior in men versus women were observed for the Turkish population. Genetic analyses showed that common environmental factors primarily contributed to smoking initiation, while genetic factors explained a greater proportion of variance in liability to nicotine dependence. Our study shows higher heritability estimate of the FTND scores and higher shared environmental influence on smoking initiation for both males and females than reported in previous studies.Öğe Statistical Analysis For Determining The Range Performance Of 155 Mm Heer/Bb Artillery Ammunition(Destech Publications, Inc, 2016) Gungor, Onur; Oncel, Ihsan Cagatay; Oncel, Sevgi Yurt155 mm MKE MOD274 HEER/Base Bleed ammunition having 39 km range at sea level can be used with NATO 52 caliber Weapon Systems. During the preparation of firing control input / tabular firing table of the projectile for T-155 Panter and T-155 Firtina, intensive data collection activities had been carried out. As well as the data that providing information about the flight characteristics of the ammunition was obtained and used to form the firing tables, those data can be used in different ways by utilizing the statistical data mining techniques. Structure of the study; Interrelated groups have been determined by using statistical methods in which muzzle velocities and range performances of two different propellant weight (5th and 6th modules/zones), two different elevation of the gun and two different weapon has been taken into consideration for the projectiles having similar weight, center of gravity and moment of inertia. Hypothesis testing and multiple linear regulation models were used to evaluate the data and find the optimum model by using 155 mm MKE MOD274 HEER/Base Bleed ammunition test data. For determination of the "range" it is apparent that there is an important role of the "muzzle velocity" and "base bleed unit" variables. However, a model describing the structure of the relationship between these variables is not very common. This study has established a new model for the 155 mm MKE MOD274 HEER/Base Bleed ammunition by linear regression analysis.Öğe Süreç ortalamasının izlenmesi için sıra istatistiklerine dayalı kalite kontrol kartları(2019) Turhan, Nejla; Oncel, Sevgi YurtBu çalışmada, herhangi bir dağılım varsayımı olmadan sıra istatistiklerine dayalı ortalamaya ilişkin kalite kontrol kartı limitlerinin belirlenmesi konusu ele alınmıştır. Dağılımdan bağımsız kontrol kartları, çarpık ya da ağır kuyruklu dağılımlar için dayanıklı bir yöntemdir. Ayrıca, çizilecek kontrol kartının dağılımının varyansını bilmeye ya da tahmin etmeye gerek yoktur. Farklı örnek hacimleri için dağılımdan bağımsız kontrol limitleri, yanlış alarm oranı ve ortalama çalışma uzunluğu hesaplamaları tablo halinde sunulmuştur. Shewhart kontrol kartı ve medyan kontol kartının çizimi hakkında bir uygulama yapılmıştır.
