The log-likelihood function \(\ell_n(\mu,\phi,\alpha,\nu)=\ln[L_n(\mu,\phi,\alpha,\nu)]\)
and parameter estimation of \( \theta=(\mu,\phi,\alpha,\nu)\) in
the quantile-based asymmetric Student's-\(t\) distribution by using the maximum likelihood estimation
are discussed in Gijbels et al. (2019a).