2.3. Modeling Workers as Hidden Markov Model.
A HMM is a statistical Markov model in which the system being modeled is assumed to be a Markov process with hidden states [49].
The hidden states are not directly visible, but output dependent on the hidden state is visible.
Each hidden state has a probability over the possible out symbol.
Hence, the sequence of observation symbols generated by an HMM gives some information about the sequence of hidden states.