KRR with |$b=1$|⁠. The labels RFF, |$s1$|⁠, |$s2$|⁠, StocQ, |$r1$|⁠, |$r2$|⁠, |$\beta $| represent |$\widehat{k}_{\text{RFF}}$|⁠, |$\widehat{k}_{s}$| for scenarios (1), (2), |$\widehat{k}_{\text{StocQ}}$|⁠, |$\widehat{k}_{\varSigma \varDelta }^{(1)}$|⁠, |$\widehat{k}_{\varSigma \varDelta }^{(2)}$| and |$\widehat{k}_{\beta }$| respectively.