We investigated two variations of this model: (i) a bidirectional LSTM model with sequential CRF layer on top (LSTM-CRF) treating the problem as a discrete classification task, (ii) a new bidirectional LSTM model with a sigmoid layer on top (LSTM-SIG) for a continuous prediction.
while the LSTM-CRF had a better (higher) F-score on the classification task, its RMS score was worse (higher) than the LSTM-SIG model, which may be due to the limitation of the model as discussed in Section 5.