TY - JOUR AU - Ray, W A TI - Evaluating medication effects outside of clinical trials: new-user designs JO - Am J Epidemiol IS - 09 VL - 158 PY - 2003 DO - 10.1093/aje/kwg231 L3 - PubMed-ID: 14585769 SP - 915 EP - 920 ER -