MID-DISTRIBUTION, MID-QUANTILE, MID P CONFIDENCE INTERVALS PROPORTION P
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
5. the Student T Distribution
Virtual Laboratories > 4. Special Distributions > 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 5. The Student t Distribution In this section we will study a distribution that has special importance in statistics. In particular, this distribution will arise in the study of a standardized version of the sample mean when the underlying distribution is normal. The Probability Density Function Suppose that Z has the standard normal distribution, V has the chi-squared distribution with n degrees of freedom, and that Z and V are independent. Let Z T= √V/n In the following exercise, you will show that T has probability density function given by −(n +1) /2 Γ((n + 1) / 2) t2 f(t)= 1 + , t∈ℝ ( n ) √n π Γ(n / 2) 1. Show that T has the given probability density function by using the following steps. n a. Show first that the conditional distribution of T given V=v is normal with mean 0 a nd variance v . b. Use (a) to find the joint probability density function of (T,V). c. Integrate the joint probability density function in (b) with respect to v to find the probability density function of T. The distribution of T is known as the Student t distribution with n degree of freedom. The distribution is well defined for any n > 0, but in practice, only positive integer values of n are of interest. This distribution was first studied by William Gosset, who published under the pseudonym Student. In addition to supplying the proof, Exercise 1 provides a good way of thinking of the t distribution: the t distribution arises when the variance of a mean 0 normal distribution is randomized in a certain way. -
Theoretical Statistics. Lecture 20
Theoretical Statistics. Lecture 20. Peter Bartlett 1. Recall: Functional delta method, differentiability in normed spaces, Hadamard derivatives. [vdV20] 2. Quantile estimates. [vdV21] 3. Contiguity. [vdV6] 1 Recall: Differentiability of functions in normed spaces Definition: φ : D E is Hadamard differentiable at θ D tangentially → ∈ to D D if 0 ⊆ φ′ : D E (linear, continuous), h D , ∃ θ 0 → ∀ ∈ 0 if t 0, ht h 0, then → k − k → φ(θ + tht) φ(θ) − φ′ (h) 0. t − θ → 2 Recall: Functional delta method Theorem: Suppose φ : D E, where D and E are normed linear spaces. → Suppose the statistic Tn : Ωn D satisfies √n(Tn θ) T for a random → − element T in D D. 0 ⊂ If φ is Hadamard differentiable at θ tangentially to D0 then ′ √n(φ(Tn) φ(θ)) φ (T ). − θ If we can extend φ′ : D E to a continuous map φ′ : D E, then 0 → → ′ √n(φ(Tn) φ(θ)) = φ (√n(Tn θ)) + oP (1). − θ − 3 Recall: Quantiles Definition: The quantile function of F is F −1 : (0, 1) R, → F −1(p) = inf x : F (x) p . { ≥ } Quantile transformation: for U uniform on (0, 1), • F −1(U) F. ∼ Probability integral transformation: for X F , F (X) is uniform on • ∼ [0,1] iff F is continuous on R. F −1 is an inverse (i.e., F −1(F (x)) = x and F (F −1(p)) = p for all x • and p) iff F is continuous and strictly increasing. 4 Empirical quantile function For a sample with distribution function F , define the empirical quantile −1 function as the quantile function Fn of the empirical distribution function Fn. -
A Tail Quantile Approximation Formula for the Student T and the Symmetric Generalized Hyperbolic Distribution
A Service of Leibniz-Informationszentrum econstor Wirtschaft Leibniz Information Centre Make Your Publications Visible. zbw for Economics Schlüter, Stephan; Fischer, Matthias J. Working Paper A tail quantile approximation formula for the student t and the symmetric generalized hyperbolic distribution IWQW Discussion Papers, No. 05/2009 Provided in Cooperation with: Friedrich-Alexander University Erlangen-Nuremberg, Institute for Economics Suggested Citation: Schlüter, Stephan; Fischer, Matthias J. (2009) : A tail quantile approximation formula for the student t and the symmetric generalized hyperbolic distribution, IWQW Discussion Papers, No. 05/2009, Friedrich-Alexander-Universität Erlangen-Nürnberg, Institut für Wirtschaftspolitik und Quantitative Wirtschaftsforschung (IWQW), Nürnberg This Version is available at: http://hdl.handle.net/10419/29554 Standard-Nutzungsbedingungen: Terms of use: Die Dokumente auf EconStor dürfen zu eigenen wissenschaftlichen Documents in EconStor may be saved and copied for your Zwecken und zum Privatgebrauch gespeichert und kopiert werden. personal and scholarly purposes. Sie dürfen die Dokumente nicht für öffentliche oder kommerzielle You are not to copy documents for public or commercial Zwecke vervielfältigen, öffentlich ausstellen, öffentlich zugänglich purposes, to exhibit the documents publicly, to make them machen, vertreiben oder anderweitig nutzen. publicly available on the internet, or to distribute or otherwise use the documents in public. Sofern die Verfasser die Dokumente unter Open-Content-Lizenzen (insbesondere CC-Lizenzen) zur Verfügung gestellt haben sollten, If the documents have been made available under an Open gelten abweichend von diesen Nutzungsbedingungen die in der dort Content Licence (especially Creative Commons Licences), you genannten Lizenz gewährten Nutzungsrechte. may exercise further usage rights as specified in the indicated licence. www.econstor.eu IWQW Institut für Wirtschaftspolitik und Quantitative Wirtschaftsforschung Diskussionspapier Discussion Papers No. -
Stat 5102 Lecture Slides: Deck 1 Empirical Distributions, Exact Sampling Distributions, Asymptotic Sampling Distributions
Stat 5102 Lecture Slides: Deck 1 Empirical Distributions, Exact Sampling Distributions, Asymptotic Sampling Distributions Charles J. Geyer School of Statistics University of Minnesota 1 Empirical Distributions The empirical distribution associated with a vector of numbers x = (x1; : : : ; xn) is the probability distribution with expectation operator n 1 X Enfg(X)g = g(xi) n i=1 This is the same distribution that arises in finite population sam- pling. Suppose we have a population of size n whose members have values x1, :::, xn of a particular measurement. The value of that measurement for a randomly drawn individual from this population has a probability distribution that is this empirical distribution. 2 The Mean of the Empirical Distribution In the special case where g(x) = x, we get the mean of the empirical distribution n 1 X En(X) = xi n i=1 which is more commonly denotedx ¯n. Those with previous exposure to statistics will recognize this as the formula of the population mean, if x1, :::, xn is considered a finite population from which we sample, or as the formula of the sample mean, if x1, :::, xn is considered a sample from a specified population. 3 The Variance of the Empirical Distribution The variance of any distribution is the expected squared deviation from the mean of that same distribution. The variance of the empirical distribution is n 2o varn(X) = En [X − En(X)] n 2o = En [X − x¯n] n 1 X 2 = (xi − x¯n) n i=1 The only oddity is the use of the notationx ¯n rather than µ for the mean. -
Depth, Outlyingness, Quantile, and Rank Functions in Multivariate & Other Data Settings Eserved@D = *@Let@Token
DEPTH, OUTLYINGNESS, QUANTILE, AND RANK FUNCTIONS – CONCEPTS, PERSPECTIVES, CHALLENGES Depth, Outlyingness, Quantile, and Rank Functions in Multivariate & Other Data Settings Robert Serfling1 Serfling & Thompson Statistical Consulting and Tutoring ASA Alabama-Mississippi Chapter Mini-Conference University of Mississippi, Oxford April 5, 2019 1 www.utdallas.edu/∼serfling DEPTH, OUTLYINGNESS, QUANTILE, AND RANK FUNCTIONS – CONCEPTS, PERSPECTIVES, CHALLENGES “Don’t walk in front of me, I may not follow. Don’t walk behind me, I may not lead. Just walk beside me and be my friend.” – Albert Camus DEPTH, OUTLYINGNESS, QUANTILE, AND RANK FUNCTIONS – CONCEPTS, PERSPECTIVES, CHALLENGES OUTLINE Depth, Outlyingness, Quantile, and Rank Functions on Rd Depth Functions on Arbitrary Data Space X Depth Functions on Arbitrary Parameter Space Θ Concluding Remarks DEPTH, OUTLYINGNESS, QUANTILE, AND RANK FUNCTIONS – CONCEPTS, PERSPECTIVES, CHALLENGES d DEPTH, OUTLYINGNESS, QUANTILE, AND RANK FUNCTIONS ON R PRELIMINARY PERSPECTIVES Depth functions are a nonparametric approach I The setting is nonparametric data analysis. No parametric or semiparametric model is assumed or invoked. I We exhibit the geometric structure of a data set in terms of a center, quantile levels, measures of outlyingness for each point, and identification of outliers or outlier regions. I Such data description is developed in terms of a depth function that measures centrality from a global viewpoint and yields center-outward ordering of data points. I This differs from the density function, -
Sampling Student's T Distribution – Use of the Inverse Cumulative
Sampling Student’s T distribution – use of the inverse cumulative distribution function William T. Shaw Department of Mathematics, King’s College, The Strand, London WC2R 2LS, UK With the current interest in copula methods, and fat-tailed or other non-normal distributions, it is appropriate to investigate technologies for managing marginal distributions of interest. We explore “Student’s” T distribution, survey its simulation, and present some new techniques for simulation. In particular, for a given real (not necessarily integer) value n of the number of degrees of freedom, −1 we give a pair of power series approximations for the inverse, Fn ,ofthe cumulative distribution function (CDF), Fn.Wealsogivesomesimpleandvery fast exact and iterative techniques for defining this function when n is an even −1 integer, based on the observation that for such cases the calculation of Fn amounts to the solution of a reduced-form polynomial equation of degree n − 1. We also explain the use of Cornish–Fisher expansions to define the inverse CDF as the composition of the inverse CDF for the normal case with a simple polynomial map. The methods presented are well adapted for use with copula and quasi-Monte-Carlo techniques. 1 Introduction There is much interest in many areas of financial modeling on the use of copulas to glue together marginal univariate distributions where there is no easy canonical multivariate distribution, or one wishes to have flexibility in the mechanism for combination. One of the more interesting marginal distributions is the “Student’s” T distribution. This statistical distribution was published by W. Gosset in 1908. -
A Tutorial on Quantile Estimation Via Monte Carlo
A Tutorial on Quantile Estimation via Monte Carlo Hui Dong and Marvin K. Nakayama Abstract Quantiles are frequently used to assess risk in a wide spectrum of applica- tion areas, such as finance, nuclear engineering, and service industries. This tutorial discusses Monte Carlo simulation methods for estimating a quantile, also known as a percentile or value-at-risk, where p of a distribution’s mass lies below its p-quantile. We describe a general approach that is often followed to construct quantile estimators, and show how it applies when employing naive Monte Carlo or variance-reduction techniques. We review some large-sample properties of quantile estimators. We also describe procedures for building a confidence interval for a quantile, which provides a measure of the sampling error. 1 Introduction Numerous application settings have adopted quantiles as a way of measuring risk. For a fixed constant 0 < p < 1, the p-quantile of a continuous random variable is a constant x such that p of the distribution’s mass lies below x. For example, the median is the 0:5-quantile. In finance, a quantile is called a value-at-risk, and risk managers commonly employ p-quantiles for p ≈ 1 (e.g., p = 0:99 or p = 0:999) to help determine capital levels needed to be able to cover future large losses with high probability; e.g., see [33]. Nuclear engineers use 0:95-quantiles in probabilistic safety assessments (PSAs) of nuclear power plants. PSAs are often performed with Monte Carlo, and the U.S. Nuclear Regulatory Commission (NRC) further requires that a PSA accounts for the Hui Dong Amazon.com Corporate LLC∗, Seattle, WA 98109, USA e-mail: [email protected] ∗This work is not related to Amazon, regardless of the affiliation. -
Nonparametric Multivariate Kurtosis and Tailweight Measures
Nonparametric Multivariate Kurtosis and Tailweight Measures Jin Wang1 Northern Arizona University and Robert Serfling2 University of Texas at Dallas November 2004 – final preprint version, to appear in Journal of Nonparametric Statistics, 2005 1Department of Mathematics and Statistics, Northern Arizona University, Flagstaff, Arizona 86011-5717, USA. Email: [email protected]. 2Department of Mathematical Sciences, University of Texas at Dallas, Richardson, Texas 75083- 0688, USA. Email: [email protected]. Website: www.utdallas.edu/∼serfling. Support by NSF Grant DMS-0103698 is gratefully acknowledged. Abstract For nonparametric exploration or description of a distribution, the treatment of location, spread, symmetry and skewness is followed by characterization of kurtosis. Classical moment- based kurtosis measures the dispersion of a distribution about its “shoulders”. Here we con- sider quantile-based kurtosis measures. These are robust, are defined more widely, and dis- criminate better among shapes. A univariate quantile-based kurtosis measure of Groeneveld and Meeden (1984) is extended to the multivariate case by representing it as a transform of a dispersion functional. A family of such kurtosis measures defined for a given distribution and taken together comprises a real-valued “kurtosis functional”, which has intuitive appeal as a convenient two-dimensional curve for description of the kurtosis of the distribution. Several multivariate distributions in any dimension may thus be compared with respect to their kurtosis in a single two-dimensional plot. Important properties of the new multivariate kurtosis measures are established. For example, for elliptically symmetric distributions, this measure determines the distribution within affine equivalence. Related tailweight measures, influence curves, and asymptotic behavior of sample versions are also discussed. -
Methods to Calculate Uncertainty in the Estimated Overall Effect Size from a Random-Effects Meta-Analysis
Methods to calculate uncertainty in the estimated overall effect size from a random-effects meta-analysis Areti Angeliki Veroniki1,2*; Email: [email protected] Dan Jackson3; Email: [email protected] Ralf Bender4; Email: [email protected] Oliver Kuss5,6; Email: [email protected] Dean Langan7; Email: [email protected] Julian PT Higgins8; Email: [email protected] Guido Knapp9; Email: [email protected] Georgia Salanti10; Email: [email protected] 1 Li Ka Shing Knowledge Institute, St. Michael’s Hospital, 209 Victoria Street, East Building. Toronto, Ontario, M5B 1T8, Canada 2 Department of Primary Education, School of Education, University of Ioannina, Ioannina, Greece 3 MRC Biostatistics Unit, Institute of Public Health, Robinson Way, Cambridge CB2 0SR, U.K | downloaded: 28.9.2021 4 Department of Medical Biometry, Institute for Quality and Efficiency in Health Care (IQWiG), Im Mediapark 8, 50670 Cologne, Germany 5 Institute for Biometrics and Epidemiology, German Diabetes Center, Leibniz Institute for Diabetes Research at Heinrich Heine University, 40225 Düsseldorf, Germany 6 Institute of Medical Statistics, Heinrich-Heine-University, Medical Faculty, Düsseldorf, Germany This article has been accepted for publication and undergone full peer review but has not https://doi.org/10.7892/boris.119524 been through the copyediting, typesetting, pagination and proofreading process which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1002/jrsm.1319 source: This article is protected by copyright. All rights reserved. 7 Institute of Child Health, UCL, London, WC1E 6BT, UK 8 Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, U.K. -
Multivariate Quantiles and Ranks Using Optimal Transportation
Multivariate Quantiles and Ranks using Optimal Transportation Bodhisattva Sen1 Department of Statistics Columbia University, New York Department of Statistics George Mason University Joint work with Promit Ghosal (Columbia University) 05 April, 2019 1Supported by NSF grants DMS-1712822 and AST-1614743 Ranks and quantiles when d = 1 X is a random variable with c.d.f. F Rank: The rank of x R is F (x) 2 Property: If F is continuous, F (X ) Unif([0; 1]) ∼ Quantile: The quantile function is F −1 Property: If F is continuous, F −1(U) F where U Unif([0; 1]) ∼ ∼ How to define ranks and quantiles in Rd , d > 1? Quantile: The quantile function is F −1 Property: If F is continuous, F −1(U) F where U Unif([0; 1]) ∼ ∼ How to define ranks and quantiles in Rd , d > 1? Ranks and quantiles when d = 1 X is a random variable with c.d.f. F Rank: The rank of x R is F (x) 2 Property: If F is continuous, F (X ) Unif([0; 1]) ∼ How to define ranks and quantiles in Rd , d > 1? Ranks and quantiles when d = 1 X is a random variable with c.d.f. F Rank: The rank of x R is F (x) 2 Property: If F is continuous, F (X ) Unif([0; 1]) ∼ Quantile: The quantile function is F −1 Property: If F is continuous, F −1(U) F where U Unif([0; 1]) ∼ ∼ Many notions of multivariate quantiles/ranks have been suggested: Puri and Sen (1971), Chaudhuri and Sengupta (1993), M¨ott¨onenand Oja (1995), Chaudhuri (1996), Liu and Singh (1993), Serfling (2010) .. -
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. -
MODELING AUTOREGRESSIVE CONDITIONAL SKEWNESS and KURTOSIS with MULTI-QUANTILE Caviar 1
WORKING PAPER SERIES NO 957 / NOVEMBER 2008 MODELING AUTOREGRESSIVE CONDITIONAL SKEWNESS AND KURTOSIS WITH MULTI-QUANTILE CAViaR by Halbert White, Tae-Hwan Kim and Simone Manganelli WORKING PAPER SERIES NO 957 / NOVEMBER 2008 MODELING AUTOREGRESSIVE CONDITIONAL SKEWNESS AND KURTOSIS WITH MULTI-QUANTILE CAViaR 1 by Halbert White, 2 Tae-Hwan Kim 3 and Simone Manganelli 4 In 2008 all ECB publications This paper can be downloaded without charge from feature a motif taken from the http://www.ecb.europa.eu or from the Social Science Research Network 10 banknote. electronic library at http://ssrn.com/abstract_id=1291165. 1 The views expressed in this paper are those of the authors and do not necessarily reflect those of the European Central Bank. 2 Department of Economics, 0508 University of California, San Diego 9500 Gilman Drive La Jolla, California 92093-0508, USA; e-mail: [email protected] 3 School of Economics, University of Nottingham, University Park Nottingham NG7 2RD, U.K. and Yonsei University, Seoul 120-749, Korea; e-mail: [email protected] 4 European Central Bank, DG-Research, Kaiserstrasse 29, D-60311 Frankfurt am Main, Germany; e-mail: [email protected] © European Central Bank, 2008 Address Kaiserstrasse 29 60311 Frankfurt am Main, Germany Postal address Postfach 16 03 19 60066 Frankfurt am Main, Germany Telephone +49 69 1344 0 Website http://www.ecb.europa.eu Fax +49 69 1344 6000 All rights reserved. Any reproduction, publication and reprint in the form of a different publication, whether printed or produced electronically, in whole or in part, is permitted only with the explicit written authorisation of the ECB or the author(s).