\begin{subequations}
\begin{align}
    \label{eq:mae}
    MAE &= \frac{1}{n} \sum_{t = W + D}^T (\hat{\beta}^t - \beta^t), \\
    \label{eq:mape}
    MAPE &= \frac{1}{n} \sum_{t = W + D}^T \frac{|\beta^t - \hat{\beta}^t|}{|\beta^t|} \times 100\%,
\end{align}    
\end{subequations}
