Emergency Department (ED) represents a highly chaotic environment with a big responsibility to provide critical care to patients on a rapid fashion for life saving service. The operating capacity of ED is often challenged with overcrowding especially with patients at non-emergency situation using it as point of access for primary care. Application of Radio Frequency Identification Device (RFID) technology in ED is gaining significant attention with the potential to improve ED care service and subsequently reduce cost. Our previous pilot study demonstrated the feasibility of quantifying patient alone time and provider time in establishing relationship to the ED length of stay (LOS). In this work, RFID data within the ED on a larger patient group was used to quantify and understand the various factors influencing `patient alone' time in ED. Results indicate that many factors such as patients per physician or nurse and order volumes are controllable to improve the operating efficiency. These findings motivates further investigation to explore the relationship of patient alone time to overall hospital LOS, readmission, patient leaving without being seen, mortality, patient satisfactions and other complications for a particular cohort of disease group to improve quality of care at ED.