AVAndrei Volodin

Andrei Volodin

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Andrei Volodin has a total of 164 co-authors. Here are the top co-authors by number of shared publications:


Latest Publications

  • Open Access

    Interval Estimation of the Ratio of Medians of the Bivariate Log-Normal Distribution

    by Pattaraporn Kidpholjaroen, Lapasrada Ritkumrop, Andrei Volodin

    The ratio of medians serves as a key metric for comparing two positively skewed populations and is especially appropriate for log-normal data, where the median more accurately represents the central tendency than the mean. This study introduces two Asymptotic confidence interval (CI) procedures for the ratio of medians of two dependent (correlated) log-normal distributions. The proposed methods utilize the Delta method and the Logarithmic transformation method and are applicable to both equal and unequal sample sizes. Their performance is assessed through extensive Monte Carlo simulation studies across a broad range of parameter settings, including varying standard deviations, correlation coefficients, and sample sizes. Moreover, a Percentile Bootstrap CI is included as a benchmark to evaluate the performance of the proposed methods for small sample sizes of n=10,20 and n=25. The methods are evaluated based on coverage probability (CP) and average width (AW). Simulation results indicate that both approaches generally achieve satisfactory CPs, while the Asymptotic approach tends to produce narrower CIs, and the Logarithmic transformation approach often provides CPs closer to the nominal confidence level, particularly for highly variable data. Two real-world datasets from Thailand, comprising PM2.5 concentration data and rainfall measurements, are used to demonstrate the practical applicability of the suggested techniques. These applications demonstrate the use of the proposed methods for interval estimation of the ratio of medians in different environmental datasets. The findings provide useful guidance for interval estimation of the ratio of medians in correlated log-normal populations.

  • Some results on complete convergence, complete moment convergence, and complete integral convergence

    by Deli Li, Andrew Rosalsky, Andrei Volodin

    1. Complete convergence, complete moment convergence, complete integral convergence, and their relationship is investigated in this article. The definitions of these concepts will be reviewed below...

  • Open Access

    On the T-Topp-Leone family of distributions for lifetime data analysis

    by Panuwat Pimsap, Winai Bodhisuwan, Andrei Volodin

    1. During the last two decades, numerous families of probability distributions have been developed to provide greater flexibility in statistical modeling. Many of these approaches are based on appl...

  • Open Access

    On the Joint Asymptotic Normality of the Method of Moments Estimators of the Two-Parameter Exponential Distribution

    by Wikanda Phaphan, Nattawut Khansai, Apitad Kraichok, Andrei Volodin

    Two-parameter exponential distribution has been widely used in research involving lifetime data, survival analysis, medical research, and reliability assessment. Since variables following this distribution are continuous, the population mean is often regarded as a key parameter of interest. In this paper, confidence intervals for the mean of a two-parameter exponential population are developed based on the joint asymptotic normality of the method of moments estimators, derived using the Delta method. The proposed asymptotic confidence intervals are compared with Wald-type confidence intervals in terms of coverage probability and average interval width. The performance of the proposed intervals is evaluated using Monte Carlo simulation, where particular attention is given to their coverage probability and mean interval width. The performance is further illustrated through a real-data application using daily PM2.5 concentration data from Bangkok, Thailand. Simulation, and the theoretical results indicate that the performance of estimators in the two-parameter exponential distribution improves as the sample size increases. Small samples lead to biased and unstable estimates, with wider confidence intervals and lower coverage probabilities, whereas moderate and large samples yield more accurate and stable results. For large samples, bias becomes negligible, variances approach the corresponding theoretical values, and coverage probabilities and interval widths approach the nominal level, confirming consistency and asymptotic efficiency.

  • Similarity-based Clustering of Probability Density Functions

    by Jen-Hao Chen, Wen-Laing Hung, Pornpiya Vikitset, Andrei Volodin

    This article proposes a similarity-based clustering framework for probability density functions (PDFs). Each PDF is represented in a finite-dimensional form, and an exponential similarity matrix is constructed from pairwise \(L_{1}\) distances. Based on this matrix, a self-organizing fixed-point iteration updates cluster representatives as convex combinations of the observed PDFs, so that the resulting centers remain in the convex hull of the data. A similarity scale parameter controls the sharpness of the weights, and the variance ratio criterion (VRC) is used to select this parameter in an objective way, thereby determining the number of clusters without requiring user-specified thresholds. From a theoretical perspective, we study the fixed points of the self-organizing updates and show that, under a mild condition on the similarity scale, the induced mapping is a contraction in the \(L_{1}\) norm. This guarantees the existence and uniqueness of the limiting cluster centers and yields a linear convergence rate for the iterative scheme. Simulation studies on synthetic PDFs demonstrate robustness to noise, outlier distributions, and severely imbalanced cluster sizes. They also show that the method can identify the correct cluster structure even when clusters overlap and the true number of clusters is unknown. Applications to a texture database and to distributions of yellow-fin tuna fork lengths further illustrate that the proposed framework provides a practical and computationally tractable tool for clustering PDF data with theoretical guarantees.

  • Jarque–Bera Test for Normality and Edgeworth Series Expansion

    by Miroslav Menshov, Andrei Volodin, Igor Volodin

    A class of distributions is determined within which the test based on the sum of the squares of the sample coefficients of skewness and kurtosis (so-called Jarque–Bera test) is the asymptotically most stringent invariant test. This class consists of Edgeworth expansions of infinitely divisible distributions. Based on the Jarque–Bera test, we propose a statistical procedure for the multiple testing of a hypothesis for normality over a large number of samples with d-risk restrictions (pFDR) of the first kind. The power properties of the d-guarantee multiple hypotheses testing are illustrated using statistical modeling data in comparison with the most commonly used Benjamini–Hochberg test. The procedure is also applied to testing the hypothesis of normality for real data arrays representing the results of observations of the expression of a gene in each member of a group of patients.

  • The Computational Fuzzy Mathematics of Mind and Compassion: A Buddhist Framework for Human-Centered Artificial Intelligence

    by Wichai Witayakiattilerd, Adoon Pansuwan, Wararit Panichkitkosolkul, Andrei Volodin

    Artificial intelligence (AI) increasingly requires internally grounded mechanisms for ethical alignment beyond rule-based supervision. We propose a Lyapunov-consistent hybrid dynamical framework Computational Fuzzy Mathematics of Mind and Compassion that integrates nonlinear state dynamics with a Sugeno-type fuzzy inference layer.The model formalizes the bounded evolution of compassion (\(M\)), wisdom (\(P\)), concentration (\(C\)), and defilements (\(H\)) on \([0,1]^{4}\), ensuring positive invariance and global Lipschitz continuity. A refined Unified Mind Integration Index (\(\textrm{UMII}_{v2}\)) provides a bounded and monotone measure of ethical coherence.Under baseline parameters, the system exhibits strictly negative Jacobian eigenvalues and local asymptotic stability. Across 1000 Monte Carlo trials with \(\pm 15\%\) parameter perturbations, trajectories consistently converge to high-coherence equilibria (UMII\({}_{\textrm{steady}}=0.81\pm 0.05)\), with strong agreement between deterministic and fuzzy estimates \((r=0.89,\;p<10^{-6})\).Simulated moral dilemmas further demonstrate robust convergence to UMII \(>0.80\), with optimal balance near \((\alpha,\beta)\approx(0.30,0.20)\). Compassion thus operates as an endogenous stabilizing state within a provably stable nonlinear architecture.These results establish a mathematically rigorous and interpretable dynamical foundation for compassion-aware AI.

  • Weighted quasi Garima distribution: properties and applications

    by Vidya Yerneni, Aafaq A. Rather, W. Madusha H. De Silva, Andrei Volodin

  • The Cosine Partially Geometric Distribution

    by Sunisa Junnumtuam, Andrei Volodin, Chom Panta

    The cosine partially geometric distribution, a weighted probability model, is introduced for analyzing over-dispersed discrete data, exemplified by weekly counts of patients over 60 diagnosed with eye inflammation in Phitsanulok province in 2021. Its key properties, including the cumulative distribution function, moment generating function, first two raw moments, and maximum likelihood estimation, are derived, highlighting its practical applicability in real-world count data modeling.

  • An Efficient Randomized Response Model Using Three Decks of Cards: A Simplified Approach to Sensitive Surveys

    by Tanveer Ahmad Tarray, Zahoor Ahmad Ganie, Gazala Salam, Yasser Farhat, Andrei Volodin, Aafaq A. Rather

    This paper substitutes the six-deck card model with an effective and respondent-friendly three-deck randomized response paradigm. Although the six-deck randomized response technique is excellent in protecting respondents’ privacy in sensitive surveys, it makes the process much complicated for them. This work would propose preserving respondent secrecy while lowering response burden and enhancing cooperation through modification of the model to use only three decks of cards. The proposed three-deck model extends the work of [1] and reveals that, in opposition to the earlier models, the maximum likelihood estimator for population percentage remains objective with reduced variance. Empirical works show that the three-deck paradigm achieves considerable efficiency gains, particularly when the share of sensitive characteristics is high or rare. These results suggest that this three-deck model, offering simplicity and privacy without any loss of statistical accuracy, may be a competitive alternative to intricate multi-deck systems.