. 2016 Nov 8;595(4):1273–1288. doi: 10.1113/JP272738

Table 3.

Impact of known covariates on grand‐averaged MEP amplitudes

Experiment	Measurement	Factor	d.f.	F value	P value
SI_1mV
Anodal stimulation	MEP_{Early epoch}	Intensity	4	3.971	0.006*
	MEP_{Early epoch}	Intensity × SI_1mV	4	2.820	0.031*
	MEP_{Late epoch}	Intensity	4	1.216	0.311
	MEP_{Late epoch}	Intensity × SI_1mV	4	1.453	0.226
Cathodal stimulation	MEP_{Early epoch}	Intensity	4	2.765	0.035*
	MEP_{Early epoch}	Intensity × SI_1mV	4	0.732	0.573
	MEP_{Late epoch}	Intensity	2.581	2.318	0.098
	MEP_{Late epoch}	Intensity × SI_1mV	2.581	1.056	0.371
Age
Anodal stimulation	MEP_{Early epoch}	Intensity	4	3.750	0.008*
	MEP_{Early epoch}	Intensity × age	4	1.659	0.169
	MEP_{Late epoch}	Intensity	4	1.594	0.185
	MEP_{Late epoch}	Intensity × age	4	1.264	0.292
Cathodal stimulation	MEP_{Early epoch}	Intensity	4	0.174	0.951
	MEP_{Early epoch}	Intensity × age	4	0.151	0.962
	MEP_{Late epoch}	Intensity	2.508	1.843	0.132
	MEP_{Late epoch}	Intensity × age	2.508	1.998	0.105
Gender
Anodal stimulation	MEP_{Early epoch}	Intensity	4	3.529	0.011*
	MEP_{Early epoch}	Intensity × gender	4	0.504	0.733
	MEP_{Late epoch}	Intensity	4	1.178	0.328
	MEP_{Late epoch}	Intensity × gender	4	0.840	0.504
Cathodal stimulation	MEP_{Early epoch}	Intensity	4	2.432	0.056
	MEP_{Early epoch}	Intensity × gender	4	1.195	0.321
	MEP_{Late epoch}	Intensity	2.456	1.881	0.125
	MEP_{Late epoch}	Intensity × gender	2.456	0.537	0.625

Repeated‐measures ANOVAs with the repeated factor of intensity were calculated for subject‐specific covariates of subject average baseline SI_1mV (stimulus intensity for 1 mV amplitude), age, and gender, against grand averaged MEPs from time bins of either the first 0–30 min (Early epoch) or the final 60–120 min (Late epoch) after tDCS stimulation. ^*Significant effects (where P < 0.05). A main interaction effect was only observed for the factor of Intensity × SI_1mV for the anodal stimulation group.