Kapral MK, Austin PC, Jeyakumar G, Hall R, Chu A, Khan AM, Jin AY, Martin C, Manuel D, Silver FL, Swartz RH, Tu JV. Rural-urban differences in stroke risk factors, incidence, and mortality in people with and without prior stroke. Circ Cardiovasc Qual Outcomes. 2019 Feb;12(2):e004973. doi: 10.1161/CIRCOUTCOMES.118.004973
Brookhart MA, Wyss MS, Layton JB, Sturmer T. Propensity score methods for confounding control in non-experimental research. Circ Cardiovasc Qual Outcomes. 2013 Sep 1;6(5):604-11. doi: 10.1161/CIRCOUTCOMES.113.000359
Huybrechts KF, Seeger JD, Rothman KJ, Glynn RJ, Avorn J, Schneeweiss S. Bias in comparative effectiveness studies due to regional variation in medical practice intensity: a legitimate concern, or much ado about nothing? Circ Cardiovasc Qual Outcomes. 2012 Sep 1;5(5):e61-4.