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Higher-Order Asymptotics
Higher-Order Asymptotics Todd Kuffner Washington University in St. Louis WHOA-PSI 2016 1 / 113 First- and Higher-Order Asymptotics Classical Asymptotics in Statistics: available sample size n ! 1 First-Order Asymptotic Theory: asymptotic statements that are correct to order O(n−1=2) Higher-Order Asymptotics: refinements to first-order results 1st order 2nd order 3rd order kth order error O(n−1=2) O(n−1) O(n−3=2) O(n−k=2) or or or or o(1) o(n−1=2) o(n−1) o(n−(k−1)=2) Why would anyone care? deeper understanding more accurate inference compare different approaches (which agree to first order) 2 / 113 Points of Emphasis Convergence pointwise or uniform? Error absolute or relative? Deviation region moderate or large? 3 / 113 Common Goals Refinements for better small-sample performance Example Edgeworth expansion (absolute error) Example Barndorff-Nielsen’s R∗ Accurate Approximation Example saddlepoint methods (relative error) Example Laplace approximation Comparative Asymptotics Example probability matching priors Example conditional vs. unconditional frequentist inference Example comparing analytic and bootstrap procedures Deeper Understanding Example sources of inaccuracy in first-order theory Example nuisance parameter effects 4 / 113 Is this relevant for high-dimensional statistical models? The Classical asymptotic regime is when the parameter dimension p is fixed and the available sample size n ! 1. What if p < n or p is close to n? 1. Find a meaningful non-asymptotic analysis of the statistical procedure which works for any n or p (concentration inequalities) 2. Allow both n ! 1 and p ! 1. 5 / 113 Some First-Order Theory Univariate (classical) CLT: Assume X1;X2;::: are i.i.d. -
The Method of Maximum Likelihood for Simple Linear Regression
08:48 Saturday 19th September, 2015 See updates and corrections at http://www.stat.cmu.edu/~cshalizi/mreg/ Lecture 6: The Method of Maximum Likelihood for Simple Linear Regression 36-401, Fall 2015, Section B 17 September 2015 1 Recapitulation We introduced the method of maximum likelihood for simple linear regression in the notes for two lectures ago. Let's review. We start with the statistical model, which is the Gaussian-noise simple linear regression model, defined as follows: 1. The distribution of X is arbitrary (and perhaps X is even non-random). 2. If X = x, then Y = β0 + β1x + , for some constants (\coefficients", \parameters") β0 and β1, and some random noise variable . 3. ∼ N(0; σ2), and is independent of X. 4. is independent across observations. A consequence of these assumptions is that the response variable Y is indepen- dent across observations, conditional on the predictor X, i.e., Y1 and Y2 are independent given X1 and X2 (Exercise 1). As you'll recall, this is a special case of the simple linear regression model: the first two assumptions are the same, but we are now assuming much more about the noise variable : it's not just mean zero with constant variance, but it has a particular distribution (Gaussian), and everything we said was uncorrelated before we now strengthen to independence1. Because of these stronger assumptions, the model tells us the conditional pdf 2 of Y for each x, p(yjX = x; β0; β1; σ ). (This notation separates the random variables from the parameters.) Given any data set (x1; y1); (x2; y2);::: (xn; yn), we can now write down the probability density, under the model, of seeing that data: n n (y −(β +β x ))2 Y 2 Y 1 − i 0 1 i p(yijxi; β0; β1; σ ) = p e 2σ2 2 i=1 i=1 2πσ 1See the notes for lecture 1 for a reminder, with an explicit example, of how uncorrelated random variables can nonetheless be strongly statistically dependent. -
Use of the Kurtosis Statistic in the Frequency Domain As an Aid In
lEEE JOURNALlEEE OF OCEANICENGINEERING, VOL. OE-9, NO. 2, APRIL 1984 85 Use of the Kurtosis Statistic in the FrequencyDomain as an Aid in Detecting Random Signals Absmact-Power spectral density estimation is often employed as a couldbe utilized in signal processing. The objective ofthis method for signal ,detection. For signals which occur randomly, a paper is to compare the PSD technique for signal processing frequency domain kurtosis estimate supplements the power spectral witha new methodwhich computes the frequency domain density estimate and, in some cases, can be.employed to detect their presence. This has been verified from experiments vith real data of kurtosis (FDK) [2] forthe real and imaginary parts of the randomly occurring signals. In order to better understand the detec- complex frequency components. Kurtosis is defined as a ratio tion of randomlyoccurring signals, sinusoidal and narrow-band of a fourth-order central moment to the square of a second- Gaussian signals are considered, which when modeled to represent a order central moment. fading or multipath environment, are received as nowGaussian in Using theNeyman-Pearson theory in thetime domain, terms of a frequency domain kurtosis estimate. Several fading and multipath propagation probability density distributions of practical Ferguson [3] , has shown that kurtosis is a locally optimum interestare considered, including Rayleigh and log-normal. The detectionstatistic under certain conditions. The reader is model is generalized to handle transient and frequency modulated referred to Ferguson'swork for the details; however, it can signals by taking into account the probability of the signal being in a be simply said thatit is concernedwith detecting outliers specific frequency range over the total data interval. -
Package 'Distributional'
Package ‘distributional’ February 2, 2021 Title Vectorised Probability Distributions Version 0.2.2 Description Vectorised distribution objects with tools for manipulating, visualising, and using probability distributions. Designed to allow model prediction outputs to return distributions rather than their parameters, allowing users to directly interact with predictive distributions in a data-oriented workflow. In addition to providing generic replacements for p/d/q/r functions, other useful statistics can be computed including means, variances, intervals, and highest density regions. License GPL-3 Imports vctrs (>= 0.3.0), rlang (>= 0.4.5), generics, ellipsis, stats, numDeriv, ggplot2, scales, farver, digest, utils, lifecycle Suggests testthat (>= 2.1.0), covr, mvtnorm, actuar, ggdist RdMacros lifecycle URL https://pkg.mitchelloharawild.com/distributional/, https: //github.com/mitchelloharawild/distributional BugReports https://github.com/mitchelloharawild/distributional/issues Encoding UTF-8 Language en-GB LazyData true Roxygen list(markdown = TRUE, roclets=c('rd', 'collate', 'namespace')) RoxygenNote 7.1.1 1 2 R topics documented: R topics documented: autoplot.distribution . .3 cdf..............................................4 density.distribution . .4 dist_bernoulli . .5 dist_beta . .6 dist_binomial . .7 dist_burr . .8 dist_cauchy . .9 dist_chisq . 10 dist_degenerate . 11 dist_exponential . 12 dist_f . 13 dist_gamma . 14 dist_geometric . 16 dist_gumbel . 17 dist_hypergeometric . 18 dist_inflated . 20 dist_inverse_exponential . 20 dist_inverse_gamma -
Fisher Information Matrix for Gaussian and Categorical Distributions
Fisher information matrix for Gaussian and categorical distributions Jakub M. Tomczak November 28, 2012 1 Notations Let x be a random variable. Consider a parametric distribution of x with parameters θ, p(xjθ). The contiuous random variable x 2 R can be modelled by normal distribution (Gaussian distribution): 1 n (x − µ)2 o p(xjθ) = p exp − 2πσ2 2σ2 = N (xjµ, σ2); (1) where θ = µ σ2T. A discrete (categorical) variable x 2 X , X is a finite set of K values, can be modelled by categorical distribution:1 K Y xk p(xjθ) = θk k=1 = Cat(xjθ); (2) P where 0 ≤ θk ≤ 1, k θk = 1. For X = f0; 1g we get a special case of the categorical distribution, Bernoulli distribution, p(xjθ) = θx(1 − θ)1−x = Bern(xjθ): (3) 2 Fisher information matrix 2.1 Definition The Fisher score is determined as follows [1]: g(θ; x) = rθ ln p(xjθ): (4) The Fisher information matrix is defined as follows [1]: T F = Ex g(θ; x) g(θ; x) : (5) 1We use the 1-of-K encoding [1]. 1 2.2 Example 1: Bernoulli distribution Let us calculate the fisher matrix for Bernoulli distribution (3). First, we need to take the logarithm: ln Bern(xjθ) = x ln θ + (1 − x) ln(1 − θ): (6) Second, we need to calculate the derivative: d x 1 − x ln Bern(xjθ) = − dθ θ 1 − θ x − θ = : (7) θ(1 − θ) Hence, we get the following Fisher score for the Bernoulli distribution: x − θ g(θ; x) = : (8) θ(1 − θ) The Fisher information matrix (here it is a scalar) for the Bernoulli distribution is as follows: F = Ex[g(θ; x) g(θ; x)] h (x − θ)2 i = Ex (θ(1 − θ))2 1 n o = [x2 − 2xθ + θ2] (θ(1 − θ))2 Ex 1 n o = [x2] − 2θ [x] + θ2 (θ(1 − θ))2 Ex Ex 1 n o = θ − 2θ2 + θ2 (θ(1 − θ))2 1 = θ(1 − θ) (θ(1 − θ))2 1 = : (9) θ(1 − θ) 2.3 Example 2: Categorical distribution Let us calculate the fisher matrix for categorical distribution (2). -
Statistical Models in R Some Examples
Statistical Models Statistical Models in R Some Examples Steven Buechler Department of Mathematics 276B Hurley Hall; 1-6233 Fall, 2007 Statistical Models Outline Statistical Models Linear Models in R Statistical Models Regression Regression analysis is the appropriate statistical method when the response variable and all explanatory variables are continuous. Here, we only discuss linear regression, the simplest and most common form. Remember that a statistical model attempts to approximate the response variable Y as a mathematical function of the explanatory variables X1;:::; Xn. This mathematical function may involve parameters. Regression analysis attempts to use sample data find the parameters that produce the best model Statistical Models Linear Models The simplest such model is a linear model with a unique explanatory variable, which takes the following form. y^ = a + bx: Here, y is the response variable vector, x the explanatory variable, y^ is the vector of fitted values and a (intercept) and b (slope) are real numbers. Plotting y versus x, this model represents a line through the points. For a given index i,y ^i = a + bxi approximates yi . Regression amounts to finding a and b that gives the best fit. Statistical Models Linear Model with 1 Explanatory Variable ● 10 ● ● ● ● ● 5 y ● ● ● ● ● ● y ● ● y−hat ● ● ● ● 0 ● ● ● ● x=2 0 1 2 3 4 5 x Statistical Models Plotting Commands for the record The plot was generated with test data xR, yR with: > plot(xR, yR, xlab = "x", ylab = "y") > abline(v = 2, lty = 2) > abline(a = -2, b = 2, col = "blue") > points(c(2), yR[9], pch = 16, col = "red") > points(c(2), c(2), pch = 16, col = "red") > text(2.5, -4, "x=2", cex = 1.5) > text(1.8, 3.9, "y", cex = 1.5) > text(2.5, 1.9, "y-hat", cex = 1.5) Statistical Models Linear Regression = Minimize RSS Least Squares Fit In linear regression the best fit is found by minimizing n n X 2 X 2 RSS = (yi − y^i ) = (yi − (a + bxi )) : i=1 i=1 This is a Calculus I problem. -
Categorical Distributions in Natural Language Processing Version 0.1
Categorical Distributions in Natural Language Processing Version 0.1 MURAWAKI Yugo 12 May 2016 MURAWAKI Yugo Categorical Distributions in NLP 1 / 34 Categorical distribution Suppose random variable x takes one of K values. x is generated according to categorical distribution Cat(θ), where θ = (0:1; 0:6; 0:3): RYG In many task settings, we do not know the true θ and need to infer it from observed data x = (x1; ··· ; xN). Once we infer θ, we often want to predict new variable x0. NOTE: In Bayesian settings, θ is usually integrated out and x0 is predicted directly from x. MURAWAKI Yugo Categorical Distributions in NLP 2 / 34 Categorical distributions are a building block of natural language models N-gram language model (predicting the next word) POS tagging based on a Hidden Markov Model (HMM) Probabilistic context-free grammar (PCFG) Topic model (Latent Dirichlet Allocation (LDA)) MURAWAKI Yugo Categorical Distributions in NLP 3 / 34 Example: HMM-based POS tagging BOS DT NN VBZ VBN EOS the sun has risen Let K be the number of POS tags and V be the vocabulary size (ignore BOS and EOS for simplicity). The transition probabilities can be computed using K categorical θTRANS; θTRANS; ··· distributions ( DT NN ), with the dimension K. θTRANS = : ; : ; : ; ··· DT (0 21 0 27 0 09 ) NN NNS ADJ Similarly, the emission probabilities can be computed using K θEMIT; θEMIT; ··· categorical distributions ( DT NN ), with the dimension V. θEMIT = : ; : ; : ; ··· NN (0 012 0 002 0 005 ) sun rose cat MURAWAKI Yugo Categorical Distributions in NLP 4 / 34 Outline Categorical and multinomial distributions Conjugacy and posterior predictive distribution LDA (Latent Dirichlet Applocation) as an application Gibbs sampling for inference MURAWAKI Yugo Categorical Distributions in NLP 5 / 34 Categorical distribution: 1 observation Suppose θ is known. -
A Statistical Test Suite for Random and Pseudorandom Number Generators for Cryptographic Applications
Special Publication 800-22 Revision 1a A Statistical Test Suite for Random and Pseudorandom Number Generators for Cryptographic Applications AndrewRukhin,JuanSoto,JamesNechvatal,Miles Smid,ElaineBarker,Stefan Leigh,MarkLevenson,Mark Vangel,DavidBanks,AlanHeckert,JamesDray,SanVo Revised:April2010 LawrenceE BasshamIII A Statistical Test Suite for Random and Pseudorandom Number Generators for NIST Special Publication 800-22 Revision 1a Cryptographic Applications 1 2 Andrew Rukhin , Juan Soto , James 2 2 Nechvatal , Miles Smid , Elaine 2 1 Barker , Stefan Leigh , Mark 1 1 Levenson , Mark Vangel , David 1 1 2 Banks , Alan Heckert , James Dray , 2 San Vo Revised: April 2010 2 Lawrence E Bassham III C O M P U T E R S E C U R I T Y 1 Statistical Engineering Division 2 Computer Security Division Information Technology Laboratory National Institute of Standards and Technology Gaithersburg, MD 20899-8930 Revised: April 2010 U.S. Department of Commerce Gary Locke, Secretary National Institute of Standards and Technology Patrick Gallagher, Director A STATISTICAL TEST SUITE FOR RANDOM AND PSEUDORANDOM NUMBER GENERATORS FOR CRYPTOGRAPHIC APPLICATIONS Reports on Computer Systems Technology The Information Technology Laboratory (ITL) at the National Institute of Standards and Technology (NIST) promotes the U.S. economy and public welfare by providing technical leadership for the nation’s measurement and standards infrastructure. ITL develops tests, test methods, reference data, proof of concept implementations, and technical analysis to advance the development and productive use of information technology. ITL’s responsibilities include the development of technical, physical, administrative, and management standards and guidelines for the cost-effective security and privacy of sensitive unclassified information in Federal computer systems. -
Chapter 5 Statistical Models in Simulation
Chapter 5 Statistical Models in Simulation Banks, Carson, Nelson & Nicol Discrete-Event System Simulation Purpose & Overview The world the model-builder sees is probabilistic rather than deterministic. Some statistical model might well describe the variations. An appropriate model can be developed by sampling the phenomenon of interest: Select a known distribution through educated guesses Make estimate of the parameter(s) Test for goodness of fit In this chapter: Review several important probability distributions Present some typical application of these models ٢ ١ Review of Terminology and Concepts In this section, we will review the following concepts: Discrete random variables Continuous random variables Cumulative distribution function Expectation ٣ Discrete Random Variables [Probability Review] X is a discrete random variable if the number of possible values of X is finite, or countably infinite. Example: Consider jobs arriving at a job shop. Let X be the number of jobs arriving each week at a job shop. Rx = possible values of X (range space of X) = {0,1,2,…} p(xi) = probability the random variable is xi = P(X = xi) p(xi), i = 1,2, … must satisfy: 1. p(xi ) ≥ 0, for all i ∞ 2. p(x ) =1 ∑i=1 i The collection of pairs [xi, p(xi)], i = 1,2,…, is called the probability distribution of X, and p(xi) is called the probability mass function (pmf) of X. ٤ ٢ Continuous Random Variables [Probability Review] X is a continuous random variable if its range space Rx is an interval or a collection of intervals. The probability that X lies in the interval [a,b] is given by: b P(a ≤ X ≤ b) = f (x)dx ∫a f(x), denoted as the pdf of X, satisfies: 1. -
Statistical Modeling Methods: Challenges and Strategies
Biostatistics & Epidemiology ISSN: 2470-9360 (Print) 2470-9379 (Online) Journal homepage: https://www.tandfonline.com/loi/tbep20 Statistical modeling methods: challenges and strategies Steven S. Henley, Richard M. Golden & T. Michael Kashner To cite this article: Steven S. Henley, Richard M. Golden & T. Michael Kashner (2019): Statistical modeling methods: challenges and strategies, Biostatistics & Epidemiology, DOI: 10.1080/24709360.2019.1618653 To link to this article: https://doi.org/10.1080/24709360.2019.1618653 Published online: 22 Jul 2019. Submit your article to this journal Article views: 614 View related articles View Crossmark data Full Terms & Conditions of access and use can be found at https://www.tandfonline.com/action/journalInformation?journalCode=tbep20 BIOSTATISTICS & EPIDEMIOLOGY https://doi.org/10.1080/24709360.2019.1618653 Statistical modeling methods: challenges and strategies Steven S. Henleya,b,c, Richard M. Goldend and T. Michael Kashnera,b,e aDepartment of Medicine, Loma Linda University School of Medicine, Loma Linda, CA, USA; bCenter for Advanced Statistics in Education, VA Loma Linda Healthcare System, Loma Linda, CA, USA; cMartingale Research Corporation, Plano, TX, USA; dSchool of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX, USA; eDepartment of Veterans Affairs, Office of Academic Affiliations (10A2D), Washington, DC, USA ABSTRACT ARTICLE HISTORY Statistical modeling methods are widely used in clinical science, Received 13 June 2018 epidemiology, and health services research to -
Principles of Statistical Inference
Principles of Statistical Inference In this important book, D. R. Cox develops the key concepts of the theory of statistical inference, in particular describing and comparing the main ideas and controversies over foundational issues that have rumbled on for more than 200 years. Continuing a 60-year career of contribution to statistical thought, Professor Cox is ideally placed to give the comprehensive, balanced account of the field that is now needed. The careful comparison of frequentist and Bayesian approaches to inference allows readers to form their own opinion of the advantages and disadvantages. Two appendices give a brief historical overview and the author’s more personal assessment of the merits of different ideas. The content ranges from the traditional to the contemporary. While specific applications are not treated, the book is strongly motivated by applications across the sciences and associated technologies. The underlying mathematics is kept as elementary as feasible, though some previous knowledge of statistics is assumed. This book is for every serious user or student of statistics – in particular, for anyone wanting to understand the uncertainty inherent in conclusions from statistical analyses. Principles of Statistical Inference D.R. COX Nuffield College, Oxford CAMBRIDGE UNIVERSITY PRESS Cambridge, New York, Melbourne, Madrid, Cape Town, Singapore, São Paulo Cambridge University Press The Edinburgh Building, Cambridge CB2 8RU, UK Published in the United States of America by Cambridge University Press, New York www.cambridge.org Information on this title: www.cambridge.org/9780521866736 © D. R. Cox 2006 This publication is in copyright. Subject to statutory exception and to the provision of relevant collective licensing agreements, no reproduction of any part may take place without the written permission of Cambridge University Press. -
Package 'Extradistr'
Package ‘extraDistr’ September 7, 2020 Type Package Title Additional Univariate and Multivariate Distributions Version 1.9.1 Date 2020-08-20 Author Tymoteusz Wolodzko Maintainer Tymoteusz Wolodzko <[email protected]> Description Density, distribution function, quantile function and random generation for a number of univariate and multivariate distributions. This package implements the following distributions: Bernoulli, beta-binomial, beta-negative binomial, beta prime, Bhattacharjee, Birnbaum-Saunders, bivariate normal, bivariate Poisson, categorical, Dirichlet, Dirichlet-multinomial, discrete gamma, discrete Laplace, discrete normal, discrete uniform, discrete Weibull, Frechet, gamma-Poisson, generalized extreme value, Gompertz, generalized Pareto, Gumbel, half-Cauchy, half-normal, half-t, Huber density, inverse chi-squared, inverse-gamma, Kumaraswamy, Laplace, location-scale t, logarithmic, Lomax, multivariate hypergeometric, multinomial, negative hypergeometric, non-standard beta, normal mixture, Poisson mixture, Pareto, power, reparametrized beta, Rayleigh, shifted Gompertz, Skellam, slash, triangular, truncated binomial, truncated normal, truncated Poisson, Tukey lambda, Wald, zero-inflated binomial, zero-inflated negative binomial, zero-inflated Poisson. License GPL-2 URL https://github.com/twolodzko/extraDistr BugReports https://github.com/twolodzko/extraDistr/issues Encoding UTF-8 LazyData TRUE Depends R (>= 3.1.0) LinkingTo Rcpp 1 2 R topics documented: Imports Rcpp Suggests testthat, LaplacesDemon, VGAM, evd, hoa,