Table 10.

Multivariable meta-regression estimates for the association of use of multiple HGP implants (yes or no) and electrical stimulation of the carcass on WBSF responses

Variable	SMD	SE	95% CI	P-value	R 2	I 2, %	τ2
Multiple implants, % of studies (KH)	0.215	0.051	0.114 to 0.315	0.001	20.4	47.4	0.035
Stimulation (reference not stimulated)
Stimulated (KH)	0.084	0.088	−0.089 to 0.257	0.654
Not stated (KH)	0.237	0.092	0.057 to 0.419	0.035
Multiple implants, % of studies (robust experiment level)	−0.030	0.069	−0.380 to 0.320	0.852			0.001
Multiple implants, % of studies (robust treatment level)	0.461	0.175	0.312 to 0.890	0.039
Stimulation (reference not stimulated)
Stimulated (robust experiment level)	0.128	0.162	−0.288 to 0.544	0.465
Not stated (robust experiment level)	0.241	0.196	−0.244 to 0.725	0.267

The estimates based on Knapp–Hartung (KH) methods provide a SMD, SE, and 95% CI of the SMD, significance (P-value), model fit (R²), and measures of heterogeneity I² and τ². The estimates based on robust regression methods (robust) at the experiment and treatment level provide a SMD, SE, and 95% CI of the SMD, P-value, and τ².