@article {gugr2009statsci, title = {Interval estimation for messy observational data}, journal = {Statistical Science}, volume = {24}, year = {2009}, pages = {328-342}, doi = {10.1214/09-sts305}, url = {http://projecteuclid.org/euclid.ss/1270041259}, author = {Gustafson, P. and Greenland, S.} }