“…However, it is rare to specify the optimum explanatory variable in advance. Further, in the case of the best subset selection or round-robin method, in which analysis is performed by utilizing all the combinations of the explanatory variables, there are 2 k − 1 combinations of k explanatory variables, resulting in a huge calculation cost (Noon et al, 2011;Saavedra et al, 2020). Additionally, based on the usefulness of each univariate regression coefficient, there are some sequential selection methods, which include forward−backward stepwise selection method, forward stepwise selection method, backward stepwise selection method, and backward−forward stepwise selection method, that sequentially increase or decrease the explanatory variables individually (Goodarzi et al, 2012;Fatima et al, 2018;Fatima et al, 2019;Hrynkiewicz et al, 2019;Fatima and Agarwal, 2020;McCann et al, 2020).…”