Figure 1. Multistage cluster sampling method for a study of the molecular epidemiology of Mycobacterium tuberculosis, Buenos Aires, Argentina, June 1, 2006–April 30, 2007. *Complete, having all but one of the following data: name, gender, date of birth or age, tuberculosis (TB) presentation, >1 sign or symptom describing the presentation and treatment received. †Unmatched controls. MDR, multidrug-resistant.