A test statistic to choose between Liu-type and least-squares estimator based on mean square error criteria

In this study, the necessary and sufficient conditions for the Liu-type (LT) biased estimator are determined. A test for choosing between the LT estimator and least-squares estimator is obtained by using these necessary and sufficient conditions. Also, a simulation study is carried out to compare this estimator against the ridge estimator. Furthermore, a numerical example is given for defined test statistic.     

Goodness of fit tests for Nakagami distribution based on smooth tests

ABSTRACT

Nakagami distribution is one of the most common distributions used to model positive valued and right skewed data. In this study, we interest goodness of fit problem for Nakagami distribution. Thus, we propose smooth tests for Nakagami distribution based on orthonormal functions. We also compare these tests with some classical goodness of fit tests such as Cramer–von Mises, Anderson–Darling, and Kolmogorov–Smirnov tests in respect to type-I error rates and powers of tests. Simulation study indicates that smooth tests give better results than these classical tests give in respect to almost all cases considered.     

On residual lifetime of coherent systems after the rth failure

In this article we study the residual lifetime of a coherent system after the rth failure, i.e. the time elapsed from the rth failure until the system failure given that the system operates at the time of the rth failure. We provide a mixture representation for the corresponding residual lifetime distribution in terms of signature. We also obtain some stochastic ordering results for the residual lifetimes.     

MARS as an alternative approach of Gaussian graphical model for biochemical networks

The Gaussian graphical model (GGM) is one of the well-known modelling approaches to describe biological networks under the steady-state condition via the precision matrix of data. In literature there are different methods to infer model parameters based on GGM. The neighbourhood selection with the lasso regression and the graphical lasso method are the most common techniques among these alternative estimation methods. But they can be computationally demanding when the system's dimension increases. Here, we suggest a non-parametric statistical approach, called the multivariate adaptive regression splines (MARS) as an alternative of GGM. To compare the performance of both models, we evaluate the findings of normal and non-normal data via the specificity, precision, F-measures and their computational costs. From the outputs, we see that MARS performs well, resulting in, a plausible alternative approach with respect to GGM in the construction of complex biological systems.     

Association of vitamin D status and the risk of cardiovascular disease as assessed by various cardiovascular risk scoring systems in patients with type 2 diabetes mellitus

Objective: The aim of the present study was to evaluate the relationship between vitamin D (25[OH]D) status and the risk of cardiovascular disease as assessed by various cardiovascular risk scoring systems such as QRISK2, BNF, ASSING, SCORE, and Framingham in patients with type 2 diabetes mellitus(T2DM).

Methods: The study included 108 patients with vitamin D insufficiency (25[OH]D?≥?10–30?ng/mL) and 100 patients with vitamin D deficiency (25[OH]D?Results: HbA1c levels were significantly higher in patients with vitamin D deficiency. Patients with vitamin D deficiency had significantly higher Framingham risk score (p?p?r?=?0.537) and a weak but statistically significant correlation between 25[OH]D levels and BNF score (r?=?0.295). 25[OH]D levels were significantly higher and HbA1c levels were significantly lower in patients with Framingham cardiovascular risk score ≤10%.

Conclusion: We found a close relationship with Framingham cardiovascular risk score in diabetic patients with very low serum vitamin D levels. Cardiovascular risk as assessed by the Framingham’s scale increases with decreasing 25[OH]D levels. BNF score was negatively correlated with 25[OH]D levels.     

Tracking public relations history in 1960s’ Turkey: The prevalence and reflections of development discourse

This study is based on a historical research, which focuses on the institutionalization of public relations in Turkey during the 1960s, and interprets this process in the frame of planned development discourse. Primary written sources collected from archive research and oral narratives generated from fourteen semi-structured interviews conducted with the pioneers in Turkey are analyzed through categorization and thematization. Findings of the historical research indicated that similar themes and orientations guided public relations practices in public and private sector in this period. Accordingly public relations education provided necessary intellectual background and human resources.     

A Midsummer Night’s Coup: Performance and Power in Turkey’s July 15 Coup Attempt

Occurring at a time when military interventions appeared to be a matter of the past, the coup attempt of July 15, 2016 left a major mark on Turkish society and politics. This article approaches the July 15 coup attempt as a contingent and transformative event and investigates how symbolic processes helped determine its immediate outcome as well as its cultural, social, and political consequences. Linking the sociological literature on events with social performance theory, the study argues that the putschists’ ineffectiveness in projecting legitimacy and power in the critical hours of the coup attempt significantly contributed to its failure. The retrospective construction of an authoritative “Narrative of July 15” in the following weeks, on the other hand, enabled the government to implement specific institutional changes in the cultural, economic, and political domains. The study proposes a two-step analysis for the cultural construction of political events and suggests that social performance theory provides useful analytical tools for tracing the course and explaining the outcome of this process.     

Demographic Data on Syrians in Turkey: What do we know?

With the outbreak of civil war in Syria, Turkey has become the host of the largest refugee population in the world. In a country where reliable population registration systems are only recently established and where no extensive legal arrangements on migration existed prior to the Syrian crisis, the whole refugee situation was handled rather unsystematically, with ever-changing institutions and regulations, and various iterations of both. In this paper we present the demographic statistics that have been made public by different sources from the beginning of the crisis up to today because they are hard to reach in one place accompanied by relevant institutional changes; with the aim of assessing the current demographic data and revealing what is missing.     

A novel feature selection scheme for high-dimensional data sets: four-Staged Feature Selection

Classification of high-dimensional data set is a big challenge for statistical learning and data mining algorithms. To effectively apply classification methods to high-dimensional data sets, feature selection is an indispensable pre-processing step of learning process. In this study, we consider the problem of constructing an effective feature selection and classification scheme for data set which has a small number of sample size with a large number of features. A novel feature selection approach, named four-Staged Feature Selection, has been proposed to overcome high-dimensional data classification problem by selecting informative features. The proposed method first selects candidate features with number of filtering methods which are based on different metrics, and then it applies semi-wrapper, union and voting stages, respectively, to obtain final feature subsets. Several statistical learning and data mining methods have been carried out to verify the efficiency of the selected features. In order to test the adequacy of the proposed method, 10 different microarray data sets are employed due to their high number of features and small sample size.     

Robust trading mechanisms over 0/1 polytopes

The problem of designing a trade mechanism (for an indivisible good) between a seller and a buyer is studied in the setting of discrete valuations of both parties using tools of finite-dimensional optimization. A robust trade design is defined as one which allows both traders a dominant strategy implementation independent of other traders’ valuations with participation incentive and no intermediary (i.e., under budget balance). The design problem which is initially formulated as a mixed-integer non-linear non-convex feasibility problem is transformed into a linear integer feasibility problem by duality arguments, and its explicit solution corresponding to posted price optimal mechanisms is derived along with full characterization of the convex hull of integer solutions. A further robustness concept is then introduced for a central planner unsure about the buyer or seller valuation distribution, a corresponding worst-case design problem over a set of possible distributions is formulated as an integer linear programming problem, and a polynomial solution procedure is given. When budget balance requirement is relaxed to feasibility only, i.e., when one allows an intermediary maximizing the expected surplus from trade, a characterization of the optimal robust trade as the solution of a simple linear program is given. A modified VCG mechanism turns out to be optimal.