Table 4. RMSE between true and estimated $\mathit{Q}$ matrices for each method and each α-prototype (rows 1 and 2); RMSE between two estimated $\mathit{Q}$ matrices (row 3); run-time (rows 4 and 5).

	${\alpha }_1$	${\alpha }_2$	${\alpha }_3$	${\alpha }_4$
$\text{RMSE}\left(Q,{\widehat{Q}}_{\text{tALS}}\right)$	$6.2\times {10}^{-2}$	$1.4\times {10}^{-2}$	$8.7\times {10}^{-3}$	$1.9\times {10}^{-1}$
$\text{RMSE}\left(Q,{\widehat{Q}}_{\text{cALS}}\right)$	$6.3\times {10}^{-2}$	$1.5\times {10}^{-2}$	$8.5\times {10}^{-3}$	$2.2\times {10}^{-1}$
$\text{RMSE}\left({\widehat{Q}}_{\text{tALS}},{\widehat{Q}}_{\text{tALS}}\right)$	$4.2\times {10}^{-3}$	$2.3\times {10}^{-3}$	$5.7\times {10}^{-4}$	$3.9\times {10}^{-2}$
tALS run time	2.6 min	1.4 min	1.5 min	2.8 min
cALS run time	4.1 hr	3.0 hr	3.5 hr	36.8 hr