“…In cases where Markov assumption is not held, using non-Markov and semi-Markov models (Chen and Tien, 2004;Ruiz-Castro and Pérez-Ocón, 2004;Kang and Lagakos, 2007;MeiraMachado et al, 2009;Foucher et al, 2010;Titman and Sharples, 2010b;Titman, 2012), and in cases where time homogeneity assumption is not held, constructing models of transition rates as time-dependent, based on parametric models; or constructing models based on piecewise constant models have been proposed as alternatives (Omar et al, 1995;Pérez-Ocón et al, 2001;Hsieh et al, 2002;Mathieu et al, 2005;Ocañ-Riola, 2005;Meira-Machado et al, 2009;Titman, 2011). But, generally, using each of these generalizations requires assessing Markov and time homogeneity assumptions because if these assumptions are held, it will be inappropriate to use more complicated models.…”