% \documentclass[serif]{beamer} % Serif for Computer Modern math font. \documentclass[serif, handout]{beamer} % Handout to ignore pause statements. \hypersetup{colorlinks,linkcolor=,urlcolor=red} \usefonttheme{serif} % Looks like Computer Modern for non-math text -- nice! \setbeamertemplate{navigation symbols}{} % Suppress navigation symbols % \usetheme{Berlin} % Displays sections on top \usetheme{Frankfurt} % Displays section titles on top: Fairly thin but still swallows some material at bottom of crowded slides %\usetheme{Berkeley} \usepackage[english]{babel} \usepackage{amsmath} % for binom \usepackage{amsfonts} % for \mathbb{R} The set of reals % \usepackage{graphicx} % To include pdf files! % \definecolor{links}{HTML}{2A1B81} % \definecolor{links}{red} \setbeamertemplate{footline}[frame number] \mode \title{Independence\footnote{ This slide show is an open-source document. See last slide for copyright information.}} \subtitle{STA 256: Fall 2018} \date{} % To suppress date \begin{document} \begin{frame} \titlepage \end{frame} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \begin{frame} \frametitle{Independence: The idea} \pause %\framesubtitle{} \begin{itemize} \item Independent means totally unrelated. \pause \item If we say that taking Vitamin C supplements in \emph{independent} of whether you get cancer\pause, it means that taking Vitamin C supplements has \emph{no connection} to whether you get cancer or not. \pause \item It's a strong statement. \pause \item It has a precise technical definition. \end{itemize} \end{frame} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \begin{frame} \frametitle{Definition of independence} %\framesubtitle{} Suppose $P(B)>0$, and $ P(A|B) = P(A)$. \pause \vspace{5mm} \begin{eqnarray*} & & \frac{P(A \cap B)}{P(B)} = P(A) \\ \pause & \Rightarrow \pause & P(A \cap B) = P(A) \, P(B) \pause \end{eqnarray*} We use this \emph{definition}. \pause We say the events $A$ and $B$ are independent when \pause {\LARGE \begin{displaymath} P(A \cap B) = P(A) \, P(B) \end{displaymath} \pause } % End size It's symmetric, and applies even if $P(A)=0$ or $P(B)=0$. \end{frame} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \begin{frame} \frametitle{Definition of \emph{mutual} independence} \framesubtitle{Of several events} \pause A set of events $A_1, \ldots, A_n$ are \emph{mutually independent} if the probability of the intersection of any sub-collection is the product of probabilities. \vspace{5mm} \pause Pairwise is not enough. \pause Example from the text, P. 24: \pause \vspace{2mm} A fair coin is tossed twice. \pause Outcomes are \hspace{3mm} HH, HT, TH, TT \pause \linebreak Let \pause \begin{itemize} \item[]$A$ = Head on first toss. \pause \item[]$B$ = Head on second toss. \pause \item[]$C$ = Exactly one Head. \pause \end{itemize} $P(A)=P(B)=P(C) = \frac{1}{2}$ \pause and they are pairwise independent\pause, but \pause $P(A \cap B \cap C) = \pause P(\emptyset) = 0 \pause \neq \frac{1}{8}$. \end{frame} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \begin{frame} \frametitle{The dice have no memory} \pause %\framesubtitle{} Successive outcomes of simple statistical experiments like flipping a coin or rolling a die will always be assumed mutually independent. \end{frame} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \begin{frame} \frametitle{Copyright Information} This slide show was prepared by \href{http://www.utstat.toronto.edu/~brunner}{Jerry Brunner}, Department of Statistical Sciences, University of Toronto. It is licensed under a \href{http://creativecommons.org/licenses/by-sa/3.0/deed.en_US} {Creative Commons Attribution - ShareAlike 3.0 Unported License}. Use any part of it as you like and share the result freely. The \LaTeX~source code is available from the course website: \vspace{5mm} \href{http://www.utstat.toronto.edu/~brunner/oldclass/256f18} {\small\texttt{http://www.utstat.toronto.edu/$^\sim$brunner/oldclass/256f18}} \end{frame} \end{document} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% $ = \{\omega \in \Omega: \}$ \begin{frame} \frametitle{} \pause %\framesubtitle{} \begin{itemize} \item \pause \item \pause \item \end{itemize} \end{frame}