Mixture responsibility (source code)

= Mixture responsibility
{title2=$\tau_{ij}=\mathbb P(Z_i=j\mid y_i)$}

A mixture responsibility is the posterior probability of a component label given an observation and current parameters: $\tau_{ij}=\pi_jf_j(y_i)/(\sum_l\pi_lf_l(y_i))$. Each observation's responsibilities sum to one. The <expectation-maximization algorithm> uses these soft assignments rather than fixed hard cluster labels.