Table going beyond the page width

Question

Why this table expands beyond the page?

\begin{table}
\caption{Class distribution in the succeeding partitions from $ A_{1} $ and $ A_{2} $}
\label{table:ClassDistribution}
\newcolumntype{R}{>{\raggedright \arraybackslash} X}
\newcolumntype{S}{>{\centering \arraybackslash} X}
\newcolumntype{T}{>{\raggedleft \arraybackslash} X}
\begin{tabularx}{\linewidth} {>{\setlength\hsize{.11\hsize}}R >{\setlength\hsize{.12\hsize}}T >{\setlength\hsize{.11\hsize}}T >{\setlength\hsize{.11\hsize}}T >{\setlength\hsize{.11\hsize}}T >{\setlength\hsize{.11\hsize}}T >{\setlength\hsize{.11\hsize}}T >{\setlength\hsize{.11\hsize}}T >{\setlength\hsize{.11\hsize}}T}  % centered columns (4 columns)
\toprule
\multicolumn{1}{c}{Splitting Attribute} & \multicolumn{1}{c}{Succeeding Partitions} & \multicolumn{3}{c}{Class Distribution} & \multicolumn{1}{c}{Gain Ratio} & \multicolumn{1}{c}{Gini Index} & \multicolumn{1}{c}{DCSM} & \multicolumn{1}{c}{m-estimate} \\
\cmidrule(l){3-5}
& & $ c_{1} $ & $ c_{1} $ & $ c_{1} $ &  &  &  &  \tabularnewline
\midrule
& $ \textbf{\textit{D}}^{A_{1}}_{1} $ & 20 & 3 & 2 &  &  &  &      \tabularnewline
\raisebox{1.5ex}{$ A_{1} $} & $ \textbf{\textit{D}}^{A_{1}}_{2} $ & 10 & 2 & 3 & \raisebox{1.5ex} 0.024 & \raisebox{1.5ex} 0.008 & \raisebox{1.5ex} 50.053 & \raisebox{1.5ex} 0.125 \tabularnewline
\midrule
 & $ \textbf{\textit{D}}^{A_{2}}_{1} $ & 20 & 5 & 0 &  &  &  &    \tabularnewline
\raisebox{1.5ex}{$ A_{2} $} & $ \textbf{\textit{D}}^{A_{2}}_{2} $ & 10 & 0 & 5 & \raisebox{1.5ex} 0.278 & \raisebox{1.5ex} 0.040 & \raisebox{1.5ex} 95.531 & \raisebox{1.5ex} 0.125 \tabularnewline
\bottomrule
\end{tabularx}
\end{table}

Answer 1

(Only now noticed your by-now month-old posting)

Why this table expands beyond the page?

It's happening because you're not permitting line breaks in the header cells, even though you're using a tabularx environment and column types that would, in principle, permit wrapping of text across lines. You must get rid of all \multicolumn{1}{c}{...} "wrappers" to re-enable line wrapping.

In addition, I would like to suggest that you (a) use \multirow statements instead of the \raisebox statements and (b) use \bm instead of \textbf\textit for math-mode material that needs to be rendered in bold italics.

\documentclass{article}
\usepackage{tabularx,booktabs,multirow,caption,bm}
% "\hspace{0pt}" directive allows hyphenation of first words in cells
\newcolumntype{R}{>{\raggedright\arraybackslash\hspace{0pt}} X}
\newcolumntype{S}{>{\centering  \arraybackslash\hspace{0pt}} X}
\newcolumntype{T}{>{\raggedleft \arraybackslash\hspace{0pt}} X}
\captionsetup{skip=0.5\baselineskip}

\begin{document}

\begin{table}
\setlength\tabcolsep{3pt}  % default value: 6pt
\caption{Class distribution in the succeeding partitions from $A_{1}$ and $A_{2}$}
\label{table:ClassDistribution}

\begin{tabularx}{\linewidth} {@{} R *{8}{S} @{}} 
\toprule
Splitting Attribute & Succeeding Partitions & \multicolumn{3}{c}Class Distribution} 
& Gain Ratio & Gini Index & DCSM & m-\hspace{0pt}estimate \\
\cmidrule(l){3-5}
& & $c_{1}$ & $c_{1}$ & $c_{1}$ \\
\midrule
\multirow{2}{*}{$A_{1}$} & $ \bm{D}^{A_{1}}_{1} $ & 20 & 3 & 2 
& \multirow{2}{*}{0.024}  & \multirow{2}{*}{0.008} 
& \multirow{2}{*}{50.053} & \multirow{2}{*}{0.125}\\
& $ \bm{D}^{A_{1}}_{2} $ & 10 & 2 & 3 & & & & \\
\midrule
\multirow{2}{*}{$A_{2}$} & $ \bm{D}^{A_{2}}_{1} $ & 20 & 5 & 0 
& \multirow{2}{*}{0.278}  & \multirow{2}{*}{0.040} 
& \multirow{2}{*}{95.531} & \multirow{2}{*}{0.125}\\
& $ \bm{D}^{A_{2}}_{2} $ & 10 & 0 & 5 &  \\
\bottomrule
\end{tabularx}

\end{table}
\end{document}

---

Addendum: As @egreg has pointed out in a comment, the four-line header cells in columns 1 and 2 don't look great. One way to fix this is to give symbolic names to the two headers in question and to provide a legend either above or below the tabular material. Another way to fix this is to widen the first two columns a bit and, correspondingly, to reduce the widths of the remaining seven columns so that the header material requires only two rows. Making X-type columns wider or narrower may be achieved by inserting various \hsize=[...]\hsize} directives; the main thing to keep in mind is that the sum of the modified hsizes has to equal the number of modified columns. In the code below, observe that 1.4+1.6+3*0.733+4*0.95=9, the total number of columns in the table. Obviously, I arrived at these column widths in part through trial and error.

\documentclass{article}
\usepackage{tabularx,booktabs,multirow,caption,bm}
\newcolumntype{R}{>{\raggedright\arraybackslash\hspace{0pt}} X}
\newcolumntype{S}{>{\centering  \arraybackslash\hspace{0pt}} X}
\newcolumntype{T}{>{\raggedleft \arraybackslash\hspace{0pt}} X}
\captionsetup{skip=0.5\baselineskip} % space below caption

\begin{document}

\begin{table}
\setlength\tabcolsep{3pt} % default value: 6pt
\caption{Class distribution in the succeeding partitions from $A_1$ and $A_2$}
\label{table:ClassDistribution}

\begin{tabularx}{\linewidth}{@{} >{\hsize=1.4\hsize}R 
                                 >{\hsize=1.6\hsize}S 
                                 *{3}{>{\hsize=0.733\hsize}S}
                                 *{4}{>{\hsize=0.950\hsize}S} @{}} 
\toprule
Splitting Attribute & Succeeding Partitions 
& \multicolumn{3}{c}{Class Distribution} & Gain Ratio 
& Gini Index & DCSM & m-\hspace{0pt}estimate \\
\cmidrule(lr){3-5}
& & $c_1$ & $c_1$ & $c_1$ \\  % is this correct?!
\midrule
\multirow{2}{*}{$A_1$} & $ \bm{D}^{A_1}_1 $ & 20 & 3 & 2 
& \multirow{2}{*}{0.024}  & \multirow{2}{*}{0.008} 
& \multirow{2}{*}{50.053} & \multirow{2}{*}{0.125}\\
& $ \bm{D}^{A_1}_2 $ & 10 & 2 & 3\\
\addlinespace[2ex]  %  insert whitespace instead of a "\midrule"
\multirow{2}{*}{$A_2$} & $ \bm{D}^{A_2}_1 $ & 20 & 5 & 0 
& \multirow{2}{*}{0.278}  & \multirow{2}{*}{0.040} 
& \multirow{2}{*}{95.531} & \multirow{2}{*}{0.125}\\
& $ \bm{D}^{A_2}_2 $ & 10 & 0 & 5 &  \\
\bottomrule
\end{tabularx}

\end{table}
\end{document}

Answer 2

This may be helpful to you. Use \scalebox{} to encase the tabularx material.

\documentclass[10pt,a4paper,oneside]{article}
\usepackage[latin1]{inputenc}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{graphicx}
\usepackage{booktabs}
\usepackage{tabularx}
\begin{document}    
\begin{table}
\caption{Class distribution in the succeeding partitions from $ A_{1} $ and $ A_{2} $}
\label{table:ClassDistribution}
\newcolumntype{R}{>{\raggedright \arraybackslash} X}
\newcolumntype{S}{>{\centering \arraybackslash} X}
\newcolumntype{T}{>{\raggedleft \arraybackslash} X}
\scalebox{0.7}{
\begin{tabularx}{\linewidth} {>{\setlength\hsize{.11\hsize}}R >{\setlength\hsize{.12\hsize}}T >{\setlength\hsize{.11\hsize}}T >{\setlength\hsize{.11\hsize}}T >{\setlength\hsize{.11\hsize}}T >{\setlength\hsize{.11\hsize}}T >{\setlength\hsize{.11\hsize}}T >{\setlength\hsize{.11\hsize}}T >{\setlength\hsize{.11\hsize}}T}  % centered columns (4 columns)
\toprule
\multicolumn{1}{c}{Splitting Attribute} & \multicolumn{1}{c}{Succeeding Partitions} & \multicolumn{3}{c}{Class Distribution} & \multicolumn{1}{c}{Gain Ratio} & \multicolumn{1}{c}{Gini Index} & \multicolumn{1}{c}{DCSM} & \multicolumn{1}{c}{m-estimate} \\
\cmidrule(l){3-5}
& & $ c_{1} $ & $ c_{1} $ & $ c_{1} $ &  &  &  &  \tabularnewline
\midrule
& $ \textbf{\textit{D}}^{A_{1}}_{1} $ & 20 & 3 & 2 &  &  &  &      \tabularnewline
\raisebox{1.5ex}{$ A_{1} $} & $ \textbf{\textit{D}}^{A_{1}}_{2} $ & 10 & 2 & 3 & \raisebox{1.5ex} 0.024 & \raisebox{1.5ex} 0.008 & \raisebox{1.5ex} 50.053 & \raisebox{1.5ex} 0.125 \tabularnewline
\midrule
 & $ \textbf{\textit{D}}^{A_{2}}_{1} $ & 20 & 5 & 0 &  &  &  &    \tabularnewline
\raisebox{1.5ex}{$ A_{2} $} & $ \textbf{\textit{D}}^{A_{2}}_{2} $ & 10 & 0 & 5 & \raisebox{1.5ex} 0.278 & \raisebox{1.5ex} 0.040 & \raisebox{1.5ex} 95.531 & \raisebox{1.5ex} 0.125 \tabularnewline
\bottomrule
\end{tabularx}
}
\end{table}
\end{document}