

\subsection{\bf Real World Confidence Levels}

\begin{slide}
\begin{itemize}
\item Unfortunately, one often gets $C(\chi^2)$ plots that look like

\vspace*{10pt}
\centerline{\psfig{figure=fig23.phys.ps,clip=true,width=3.0in}}
\vspace*{10pt}

\item with no clear ``flat'' piece.  

\item This maybe because your ``signal'' is very small.  

\item It could be because you got your errors wrong (!), e.g.,
maybe the true $\sigma_i$ are all larger than ones used in calculating
$\chi^2$.  

\item In this case, it makes sense to scale $\chi^2 \left(
\chi^2_{\rm new} = \mbox{const.}\ \chi^2_{\rm old} \right)$ until we
get a nice flat distribution for confidence level $C$ near 1 and
analyze as above.
\end{itemize}
\end{slide}

