TY  - JOUR
T1  - PErsonal health records and medical care use—reply
AU  - Palen TE
Y1  - 2013/02/27
N1  - 10.1001/jama.2013.384
JO  - JAMA
SP  - 767
EP  - 768
VL  - 309
IS  - 8
N2  - 
I also agree that volunteer bias is a potential problem not only for retrospective studies such as ours, but also for all observational research studies. We attempted to control for volunteer bias in our study by having each cohort serve as their own control and by performing both intracohort and intercohort analyses. Volunteer bias is controlled within a trial by randomization, but it still may occur when patients, clinicians, or sites decide whether to participate.

SN  - 0098-7484
M3  - doi: 10.1001/jama.2013.384
UR  - http://dx.doi.org/10.1001/jama.2013.384
ER  -