Table 2 Factor analysis of perception items (rotated component matrix)

Perception item	Factor
Perception item	RA	EU	Trialability
Using Patient Gateway^a will improve the quality of care I receive (RA^b)	0.832	0.184	0.243
Using Patient Gateway will enable me to contact my doctor’s office more easily (RA)	0.781	0.274	0.291
Using Patient Gateway will enable me to contact my doctor’s office more quickly (RA)	0.747	0.250	0.318
Using Patient Gateway will give me greater control over my care (RA)	0.699	0.254	0.320
The effectiveness of care I receive will not improve by my using Patient Gateway (RA)	−0.642	−0.125	0.089
Using Patient Gateway will require a lot of mental effort (EU)	−0.154	−0.857	−0.087
Using Patient Gateway will be frustrating (EU)	−0.299	−0.833	−0.173
Learning to use Patient Gateway will be easy for me (EU)	0.253	0.726	0.436
Overall, I believe that Patient Gateway will be easy to use (EU)	0.355	0.712	0.423
I will not lose much by trying Patient Gateway, even if I do not like it (Trialability)	0.109	0.188	0.821
I will try Patient Gateway on a trial basis to see what it can do for me (Trialability)	0.168	0.158	0.814
I will have adequate opportunities to try Patient Gateway to see what it can do (Trialability)	0.287	0.274	0.725
Eigen value	6.2	1.3	1.1
Percent variance	26.5	23.7	21.9
Cronbach’s Alpha for scale	0.86	0.90	0.82
Mean of scale (SD): Adopter Non-adopter	3.8 (0.71) 3.2 (0.89)	4.1 (0.71) 3.3 (0.95)	4.0 (0.57) 3.4 (0.99)
p-value for adopter versus non-adopter	0.000	0.000	0.000

↵a Patient Gateway is the patient portal used by the practices and patients in this study. For non-adopters, we substituted the term electronic personal health record for Patient Gateway.
↵b Refers to the perceived attribute from the DOI model: RA, Relative Advantage; EU, Ease of Use.