\begin{table}%T2 \par \caption{\label{table-bias}Biases in the size determination.} \small %\centerline { \begin{tabular}{cc|c} \hline\hline $\xi$$^a$ & Absorption$^b$ & $R/X_{\rm OCP}$$^c$ \\ \hline 0.35 & YES & 0.975 \\ 0.30 & YES & 0.970 \\ 0.25 & YES & 0.961 \\ \hline 0.35 & NO & 1.012 \\ 0.30 & NO & 0.995 \\ 0.25 & NO & 0.977 \\ \hline \end{tabular}} \smallskip $^a$ {$\xi$ refers to the shell width in units of the source radius (fractional shell width) of the model.}\\ $^b$ {Absorption refers to a blockage of all the emission coming from the part of the shell behind the ejecta (see text).} \\ $^c$ {Ratio of model source size, $R$, to size determined with the CPM, $X_{\rm OCP}$.} \end{table}