Delimiters -- appropriate usage

Question

What is the appropriate LaTeX when I do not want a closing right bracket? Alternatively, should I setup the left bracket differently?

\begin{align*}
  r_{sj} &= 
  \left\{ \begin{array}{lc} 
     1 & \text{if $Y_j$ is observed in $s$} \\
     0 & \text{if $Y_j$ is missing in $s$} 
  \end{array} \right
\end{align*}

Here, I do not wish to have \right\} in the text.

But I get a missing delimiter error on compiling

Answer 1

For this kind of thing there is the cases environment. If the second columns primarily consists of text, you might want to use cases* from mathtools. If you had some other construction, where cases does not apply, you can insert an “empty” delimiter using . as in \right..

\documentclass{article}
\usepackage{mathtools}% load amsmath

\begin{document}

\begin{equation*}
  r_{sj} = 
  \begin{cases*}
     1 & if $Y_j$ is observed in $s$ \\
     0 & if $Y_j$ is missing in $s$ \\
  \end{cases*}
\end{equation*}

\end{document}