作者cicatrix (事情多一点也好)
看板YZUfinGrad95
标题[闲聊] 砚评我弄了一部份这个
时间Sat Sep 22 03:16:27 2007
\documentclass[14pt,a4paper]{article}
\title{Dummy Variables}
\author{叶锦徽}
\date{2007.09.22}
\begin{document}
\maketitle
\fontsize{12}{20pt}\selectfont
\section{\textbf What are Dummy Variables?}
\subsection {Type of measurement:}
\begin{itemize}
\item nominal scale:名目,ex:交通工具。
\item ordinal scale:排序,ex:问卷之强弱选项。
\item interval scale:等距,ex:高低与大小有意义。
\item ratio scale:等比,最重要。
\end{itemize}
\medskip
\subsection {Nominal scale:}
\begin{itemize}
\item indicator
\item categorical
\item qualitative
\item dummy
\end{itemize}
$<eg>$:sex,race,religion,nation,...。\\
$\rightarrow$ Used to classify data into mutually exclusive categories.\\
$\rightarrow$ No natural scale of measurement.
\medskip
\section{\textbf Regression Model with Dummy Variables as Regressors}
\begin{itemize}
\item with only dummy variables $\gg$ ANOVA
\item with both DVs and quantitative variables $\gg$ ANCOVA
\end{itemize}
\bigskip
\subsection {Regression ANOVA}
$<\textbf{ex}>$9.1 1985年 50 states,salary of public school teachers:\\
分成三区:\\
$\diamond$东北与中北部\hfill (21洲)平均 $\$$24,424\\
$\diamond$南部\hfill (17洲)平均 $\$$22,894\\
$\diamond$西部\hfill (13洲)平均 $\$$26,158\\
$\longrightarrow$ Are they statisitcally different?
\bigskip
\raggedright Model:\\
$Y_{i}$=$\beta_{1}+\beta_{2}D_{2i}+\beta_{3i}+u_{i}$\\
$\rightarrow$What's the story behind?\\
\medskip
$E[Y_{i}|D_{2}=1,D_{3}=1]=\beta_{1}+\beta_{2}$ $\longrightarrow$ average
salary for NE $\&$ NC \\
$E[Y_{i}|D_{2}=0,D_{3}=1]=\beta_{1}+\beta_{3}$ $\longrightarrow$ mean salary
for S \\
$E[Y_{i}|D_{2}=0,D_{3}=0]=\beta_{1}$ $\longrightarrow$ benchmark sample
(West) \\
\bigskip
$\beta_{2}$ means the difference in mean salary between states in NE $\&$ NC
in comparison with those in W.\\
$\beta_{3}$ means the difference in mean salary between states in South in
comparison with those in W.\\
\bigskip
$\longrightarrow$
$Y_{i}=86,158-1734D_{2i}-3264D_{3i}$\\
\hspace{1.2cm}t=(23.18)\hspace{0.8cm}(-1.21)\hspace{0.8cm}(-2.18)
\end{document}
你把以上的东西丢到winedt去看一下
这麽多也不过才0.7页左右而已
不过今天晚上算是有点收获 .............
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1F：推 CarreraF91:喔喔...真不愧小白...谢啦^^ 09/22 13:08
2F：→ man519519:真贴心 09/22 17:37