Bowater RJ, Hartley LC, Lilford RJ. Are cardiovascular trial results systematically different between North America and Europe? A study based on intra-meta-analysis comparisons. Arch Cardiovasc Dis. 2015 Jan;108(1):23-38. doi: 10.1016/j.acvd.2014.03.005
Poole WK, Pollack M, Rapoport I, Williams V, Koch MA, Rao AV, Bartel DA. Use of Multivariate Methods in Quantifying the Variability in the Perception of Neonatal Intensive Care Unit Characteristics in Nine Hospitals in the Washington, DC Area: the NIH-DC Initiative to Reduce Infant Mortality in Minority Populations in the District of Columbia. Interstat. 2002 Jan 1.