We consider estimation of the causal effect of a treatment on an outcome from observational data collected in two phases. In the first phase, a simple random sample of individuals is drawn from a population. On these individuals, information is obtained on treatment, outcome and a few low...

Background: Injury is the leading cause of death for persons aged 1-44 years in the United States. Injuries have a substantial economic cost. For that reason, regional systems of trauma care in which the more acutely injured patients are transported to Level-I (L-I) trauma centers (TCs) has been...

Rheumatoid arthritis is a progressive, disabling disease which can lead to long-term deformity and disability. Leflunomide is a disease-modifying antirheumatic drug (DMARD) approved to reduce signs and symptoms, inhibit structural damage and improve physical function in adults with active...

Type 2 diabetes mellitus is a progressive disease with an insidious onset. It is thought to affect up to 10% of European and North American populations with a significantly higher incidence in non-White than in White populations. Complications of the disease are associated with considerable...