title: Negative controls: a tool for detecting confounding and bias in observational studies.
authors.affiliation: Department of Epidemiology, Center for Communicable Disease Dynamics, Harvard School of Public Health, Boston, MA 02115, USA. mlipsitc@hsph.harvard.edu
authors.forename: Marc
authors.initials: M
authors.lastname: Lipsitch
authors.forename: Eric
authors.initials: E
authors.lastname: Tchetgen Tchetgen
authors.forename: Ted
authors.initials: T
authors.lastname: Cohen