Sujit K. Sahu’s research while affiliated with University of Southampton and other places

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Publications (83)


Efficient Bayesian Estimation of Spatial Poisson Auto-regression with Leroux Random Effects
  • Chapter

January 2025

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3 Reads

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Sujit K. Sahu

A Bayesian spatio-temporal Poisson auto-regressive model for the disease infection rate: application to COVID-19 cases in England

November 2024

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22 Reads

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3 Citations

Journal of the Royal Statistical Society Series C Applied Statistics

The COVID-19 pandemic provided new modelling challenges to investigate epidemic processes. This paper extends Poisson auto-regression to incorporate spatio-temporal dependence and characterize the local dynamics by borrowing information from adjacent areas. Adopted in a fully Bayesian framework and implemented through a novel sparse-matrix representation in Stan, the model has been validated through a simulation study. We use it to analyse the weekly COVID-19 cases in the English local authority districts and verify some of the epidemic-driving factors. The model detects substantial spatio-temporal heterogeneity and enables the formalization of novel model-based investigation methods for assessing additional aspects of disease epidemiology.



Introduction to Probability

April 2024

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10 Reads

Chapter 3: The basic concepts of probability are introduced in this chapter. Elementary methods of counting, the number of permutations and the number of combinations are introduced and illustrated. Elementary methods for calculating probabilities are discussed and the general urn problem in probability is defined.


Hypothesis Testing

April 2024

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186 Reads

Chapter 12 discusses testing of statistical hypotheses called null and alternative hypothesis. Definintions of many related keywords, e.g. critical region, types of errors while testing statistical hypothesis, power function, sensitivity and specificity are provided. These are illustrated with the t-test for testing hypothesis regarding the mean of one ir two normal distributions. This chapter ends with a discussion on designs of experiments for estimation and testing purposes.


Standard Continuous Distributions

April 2024

Chapter 7: This chapter introduces standard continuous distributions: exponential, normal, gamma and beta. As in Chap. 6, here we find the means and variances and also discuss the R commands for finding various quantities for each distribution.



Conditional Probability and Independence

April 2024

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7 Reads

Chapter 4: This chapter introduces many advanced laws of probability such as the total probability theorem, conditional probability and the Bayes theorem. The famous Monty Python problem is discussed and illustrated using a simulation tool in R. The concept of independence is discussed and illustrated with many examples such system reliability and randomised response methods.


Getting Started with R

April 2024

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4 Reads

Chapter 2: This chapter introduces the R software package and discusses how to get started with many examples. It revisits some of the data sets already mentioned in Chap. 1 by drawing simple graphs and obtaining summary statistics.


Introduction to Basic Statistics

April 2024

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40 Reads

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1 Citation

Chapter 1: This chapter introduces basic statistics such as the mean, median and mode and standard deviation. It also provides introduction to many motivating data sets which are used as running examples throughout the book. An accessible discussion is also provided to debate issues like: “Lies, damned lies and statistics” and “Figures don’t lie but liars can figure.”


Citations (49)


... It was found that the shapes of the diagrams were close to ellipse, and they also met the assumption of multivariate normality and linearity (Çokluk et al., 2012). There is no autocorrelation between the variables tested with the Durbin-Watson (DW) statistic (DW = 2.005), and the multivariate kurtosis critical ratio was less than 10 (Küçüksille, 2014). Accordingly, maximum likelihood was used as the estimation method. ...

Reference:

Computational thinking in primary school: effects of student and school characteristics
Multiple Linear Regression Model
  • Citing Chapter
  • December 2023

... Instead of representing estimates as single values, these intervals provide a range that quantifies potential errors, offering a more comprehensive view of the underlying data [26]. By identifying and eliminating the causes of uncertainty, researchers can find better statistical methods with lower levels of uncertainty, thus enhancing their decision-making processes [27]. This uncertainty evaluation is essential across all scientific disciplines, as statistical methods provide the foundation for data analysis and scientific inquiry. ...

Introduction to Basic Statistics
  • Citing Chapter
  • April 2024

... The WHO and UNICEF produce WHO-UNICEF Estimates of National Immunization Coverage (WUENIC), synthesizing information from national reports, standardized surveys, and other credible data streams [70]. The triangulation aims to produce a more robust and comprehensive picture of vaccination efforts, correcting for potential underreporting or reporting lags. ...

Bayesian hierarchical modelling approaches for combining information from multiple data sources to produce annual estimates of national immunization coverage
  • Citing Preprint
  • File available
  • November 2022

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Warren C. Jochem

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Marta Gacic-Dobo

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... Following previous work [17][18][19]27,28], we assembled a suite of geospatial covariate information for our analysis. This included remoteness (e.g., distance to roads and travel time to the nearest health facility), socioeconomic (e.g., nightlight intensity, livestock density) and environmental (e.g., elevation, temperature and precipitation) variables-see, e.g., Supplementary Table S1. ...

Conditional probability and ratio-based approaches for mapping the coverage of multi-dose vaccines

Statistics in Medicine

... Specifically, regression analysis was conducted for the effects of social and economic risk factors [13,22,27,33,40], time-series models were utilized to deal with temporal dependency throughout the pandemic [25,5] and spatial models have been employed for understanding the diffusion of COVID-19 spread [10]. Other recent studies attempted to build efficient methods that incorporate both time and space effects in order to model COVID-19's dynamics [11,28,30,38]. ...

Editorial: Spatio-temporal dynamics of Covid
  • Citing Article
  • January 2022

Spatial Statistics

... Spatiotemporal forecasting (and explanation) is challenging because of the characteristics of spatiotemporal data. Particularly, spatiotemporal dependence and variability, and nonlinearity in the data violate the white noise assumption for the error term (Sahu and Böhning 2021). Giacomini and Granger (2004) showed that ignoring spatial dependence in spatiotemporal forecasting can lead to highly inaccurate forecasts. ...

Bayesian spatio-temporal joint disease mapping of Covid-19 cases and deaths in local authorities of England
  • Citing Article
  • May 2021

Spatial Statistics

... The long-term trend of Chl-a sat over the oligotrophic waters of the ocean gyres has been studied without a general agreement between increase (McClain et al., 2004;Aiken et al., 2017;Hammond et al., 2020;Cael et al., 2023) or decrease (Vantrepotte and Mélin, 2011;Signorini et al., 2015). The opposite trend observed between studies is mainly related to the spatiotemporal coverage. ...

Regional surface chlorophyll trends and uncertainties in the global ocean

... When using machine learning methods in this setting, there is no obvious quantification of sampling error in most cases (Faraway & Augustin, 2018). For example, when one uses a random forest model (Breiman, 2001a), one can calculate a metric to assess the predictive performance of the model (e.g., RMSE) and extract a predictor importance metric (e.g., permutation importance; Breiman, 2001a); but in most applications, we do not see standard errors nor p values associated with these quantities (R. Sambasivan et al., 2020) 3 . ...

A Bayesian perspective of statistical machine learning for big data

Computational Statistics

... The experts selected questions and reviewed them in terms of their social and cultural universality, overlap with the minimal ICF generic set [13] and statistical criteria. In a second step, the robustness and reliability of the selection the expert proposed were tested using Generalized Partial Credit Model (GPCM) and Bayesian models adjusted for age, gender and income were estimated [14]. ...

A Full Bayesian Implementation of A Generalized Partial Credit Model with an Application to an International Disability Survey
  • Citing Article
  • September 2019

Journal of the Royal Statistical Society Series C Applied Statistics