\documentclass[12pt]{report} %%%%% title %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \title{\tr{Introduction to Scientific Computing}{Einf\"uhrung in die wissenschaftliche Datenverarbeitung}} \author{Jan Benda\\Abteilung Neuroethologie\\[2ex]\includegraphics[width=0.3\textwidth]{UT_WBMW_Rot_RGB}} \date{WS 15/16} %%%% language %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % \newcommand{\tr}[2]{#1} % en % \usepackage[english]{babel} \newcommand{\tr}[2]{#2} % de \usepackage[german]{babel} %%%%% packages %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \usepackage{pslatex} % nice font for pdf file \usepackage[breaklinks=true,bookmarks=true,bookmarksopen=true,pdfpagemode=UseNone,pdfstartview=FitH,colorlinks=true,citecolor=blue]{hyperref} %%%% layout %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \usepackage[left=25mm,right=25mm,top=20mm,bottom=30mm]{geometry} \setcounter{tocdepth}{1} %%%%% section style 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\setcounter{maxexercise}{9} % show listings up to exercise maxexercise \newcounter{theexercise} \setcounter{theexercise}{1} \newenvironment{exercise}[1][]{\medskip\noindent\textbf{\tr{Exercise}{\"Ubung} \arabic{theexercise}:}\newline \newcommand{\exercisesource}{#1}}% {\ifthenelse{\equal{\exercisesource}{}}{}{\ifthenelse{\value{theexercise}>\value{maxexercise}}{}{\medskip\lstinputlisting{\exercisesource}}}\medskip\stepcounter{theexercise}} \graphicspath{{figures/}} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \begin{document} \include{statistics} \end{document} \end{document} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \section{Statistics} What is "a statistic"? % dt. Sch\"atzfunktion \begin{definition}[statistic] A statistic (singular) is a single measure of some attribute of a sample (e.g., its arithmetic mean value). It is calculated by applying a function (statistical algorithm) to the values of the items of the sample, which are known together as a set of data. \source{http://en.wikipedia.org/wiki/Statistic} \end{definition} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \section{Data types} \subsection{Nominal scale} \begin{itemize} \item Binary \begin{itemize} \item ``yes/no'', \item ``true/false'', \item ``success/failure'', etc. \end{itemize} \item Categorial \begin{itemize} \item cell type (``rod/cone/horizontal cell/bipolar cell/ganglion cell''), \item blood type (``A/B/AB/0''), \item parts of speech (``noun/veerb/preposition/article/...''), \item taxonomic groups (``Coleoptera/Lepidoptera/Diptera/Hymenoptera''), etc. \end{itemize} \item Each observation/measurement/sample is put into one category \item There is no reasonable order among the categories.\\ example: [rods, cones] vs. [cones, rods] \item Statistics: mode, i.e. the most common item \end{itemize} \subsection{Ordinal scale} \begin{itemize} \item Like nominal scale, but with an order \item Examples: ranks, ratings \begin{itemize} \item ``bad/ok/good'', \item ``cold/warm/hot'', \item ``young/old'', etc. \end{itemize} \item {\bf But:} there is no reasonable measure of {\em distance} between the classes \item Statistics: mode, median \end{itemize} \subsection{Interval scale} \begin{itemize} \item Quantitative/metric values \item Reasonable measure of distance between values, but no absolute zero \item Examples: \begin{itemize} \item Temperature in $^\circ$C ($20^\circ$C is not twice as hot as $10^\circ$C) \item Direction measured in degrees from magnetic or true north \end{itemize} \item Statistics: \begin{itemize} \item Central tendency: mode, median, arithmetic mean \item Dispersion: range, standard deviation \end{itemize} \end{itemize} \subsection{Absolute/ratio scale} \begin{itemize} \item Like interval scale, but with absolute origin/zero \item Examples: \begin{itemize} \item Temperature in $^\circ$K \item Length, mass, duration, electric charge, ... \item Plane angle, etc. \item Count (e.g. number of spikes in response to a stimulus) \end{itemize} \item Statistics: \begin{itemize} \item Central tendency: mode, median, arithmetic, geometric, harmonic mean \item Dispersion: range, standard deviation \item Coefficient of variation (ratio standard deviation/mean) \item All other statistical measures \end{itemize} \end{itemize} \subsection{Data types} \begin{itemize} \item Data type selects \begin{itemize} \item statistics \item type of plots (bar graph versus x-y plot) \item correct tests \end{itemize} \item Scales exhibit increasing information content from nominal to absolute.\\ Conversion ,,downwards'' is always possible \item For example: size measured in meter (ratio scale) $\rightarrow$ categories ``small/medium/large'' (ordinal scale) \end{itemize} \subsection{Examples from neuroscience} \begin{itemize} \item {\bf absolute:} \begin{itemize} \item size of neuron/brain \item length of axon \item ion concentration \item membrane potential \item firing rate \end{itemize} \item {\bf interval:} \begin{itemize} \item edge orientation \end{itemize} \item {\bf ordinal:} \begin{itemize} \item stages of a disease \item ratings \end{itemize} \item {\bf nominal:} \begin{itemize} \item cell type \item odor \item states of an ion channel \end{itemize} \end{itemize}