

\subsection{\bf Several Parameters in}
\subsection{\bf Method of Moments---I}

\begin{slide}
\begin{itemize}
\item As we have already mentioned, the case of several parameters is
treated by taking several moments.  

\item Now our moment errors are described by a full second moment
matrix for off diagonal terms come from ${\displaystyle\int} (f(x) -
\langle f\rangle)\, (g(x) - \langle g\rangle )\, p(x)\, dx$ which is
nonzero in general.

\item It is conventional to ignore correlations:  

\begin{description}
\item{$\bullet$} The expansion in terms of $Y^l_m (\theta ,\varphi)$ of
$d\sigma/dt$ or an angular decay distribution is typical example.

\item{$\bullet$} The expansion functions $Y^l_m$ are orthonormal, so
\begin{eqnarray*}
W(\theta , \varphi ) & = & \sum_{lm} a_{lm} Y_{lm} \\
a_{lm} & \propto & \langle Y^*_{lm} \rangle
\end{eqnarray*}
\end{description}
\end{itemize}
\end{slide}

