[Tex/LaTex] Bigger brackets

Question

I would like to get the two outer brackets are bigger than the others. How can this be done? I've tried using \big before the first bracket but that didn't work

\Corr (\left(a^{-j}\right)}^tX_j, {\left(b^{-j}\right)}^tY_j)

Answer 1

\left and \right can be nested:

\documentclass{article}
\begin{document}
\[
  \left(\left(a^{-j}\right)^t X_j, \left(b^{-j}\right)^t Y_j\right)
\]
\end{document}

Also the enlargement of the inner brackets is not really necessary:

\documentclass{article}
\begin{document}
\[
  \left((a^{-j})^t X_j, (b^{-j})^t Y_j\right)
\]
\end{document}