Table 3.

Parameter estimates of the complex model with 12 estimated parameters (Nominal) and the reduced models with five sensitive parameters selected by FIM and LASSO methods (${\widehat{\theta }}^{\mathrm{F}\mathrm{I}\mathrm{M}}$ and ${\widehat{\theta }}^{\mathrm{L}\mathrm{A}\mathrm{S}\mathrm{S}\mathrm{O}}$, respectively). Parameter 95% confidence interval width was estimated for the complex and reduced models. Goodness of fit was measured by $\mathrm{V}\mathrm{A}\mathrm{F}$. All values are given as mean $\pm$standard deviation across subjects.

Parameters	Parameter estimates			95% confidence interval width
$\mathrm{\Theta }$	$\widehat{\mathrm{\Theta }}$ (Nominal)	${\widehat{\theta }}^{\mathrm{F}\mathrm{I}\mathrm{M}}$	${\widehat{\theta }}^{\mathrm{L}\mathrm{A}\mathrm{S}\mathrm{S}\mathrm{O}}$	$\mathrm{C}\mathrm{I}\left(\mathrm{\Theta }\right)$	$\mathrm{C}\mathrm{I}\left({\theta }^{\mathrm{F}\mathrm{I}\mathrm{M}}\right)$	$\mathrm{C}\mathrm{I}\left({\theta }^{\mathrm{L}\mathrm{A}\mathrm{S}\mathrm{S}\mathrm{O}}\right)$
$K_{\text{vis}}(\frac{\text{Nm}}{\text{rad}})$	428 ± 125	279a,b ± 27	401 ± 163	546 ± 128	62c,d ± 19	236c ± 122
$K_{\text{vcr}}(\frac{{\text{Nms}}^2}{\text{rad}})$	4860 ± 2205	—	8055a ± 1371	7274 ± 806	—	3623c ± 1418
$K_{\text{ccr}}(\frac{\text{Nm}}{\text{rad}})$	87.9 ± 55.3	16.2a,b ± 11.9	36.4a ± 30.5	123.0 ± 49.8	18.2c,d ± 6.0	68.7c ± 36.9
$\tau (\mathrm{s})$	0.263 ± 0.027	0.242b ± 0.024	0.226a ± 0.027	0.034 ± 0.010	0.020c,d ± 0.0710	0.033 ± 0.010
${\tau }_{1\mathrm{A}}(\mathrm{s})$	0.099 ± 0.063	0.069 ± 0.013	—	0.134 ± 0.036	0.030c ± 0.015	—
${\tau }_{\text{CNS}1}(\mathrm{s})$	0.675 ± 0.280	0.918a ± 0.077	—	0.544 ± 0.145	0.138c ± 0.069	—
${\tau }_{\mathrm{c}}(\mathrm{s})$	1.733 ± 1.118	—	2.200 ± 1.256	3.086 ± 0.495	—	1.736c ± 0.534
${\tau }_{\text{CNS}2}(\mathrm{s})$	27.2 ± 16.2	—	—	48.7 ± 2.4	—	—
${\tau }_{\text{MS}1}(\mathrm{s})$	0.433 ± 0.381	—	—	0.932 ± 0.075	—	—
${\tau }_{\text{MS}2}(\mathrm{s})$	0.439 ± 0.325	—	—	0.877 ± 0.086	—	—
$B(\frac{\text{Nms}}{\text{rad}})$	1.690 ± 1.213	—	—	4.659 ± 0.144	—	—
$K(\frac{\text{Nm}}{\text{rad}})$	2.170 ± 1.736	—	—	4.758 ± 0.114	—	—
$\mathrm{V}\mathrm{A}\mathrm{F}\hspace{0.17em}(\%)$	82.26 ± 7.67	82.65 ± 7.57	81.87 ± 7.56	—	—	—

^aThe parameter estimate in the reduced model (with five estimated parameters selected by FIM and LASSO methods) was significantly different (p ≤ 0.05) from that of the complex model (with 12 estimated parameters – nominal values).

^bThe parameter estimate in the FIM-selected parameters was significantly different (p ≤ 0.05) from that of the LASSO-selected parameters.

^cThe parameter 95% confidence interval in the reduced model (from FIM or LASSO methods) was significantly narrower (p ≤ 0.05) than that of the complex model.

^dThe parameter 95% confidence interval from the FIM method was significantly narrower (p ≤ 0.05) than that from the LASSO method.