This book presents a comprehensive study of estimation methods for two-stage open queueing networks, with and without feedback. It develops practical, distribution-free approaches to estimate traffic intensities, intensity vectors, and mean response times using consistent estimators and multiple bootstrap techniques, including standard, percentile, bias-corrected, accelerated, Bayesian, and bootstrap-t methods. Through detailed simulation studies, the book evaluates coverage accuracy, interval length, and efficiency of each method, highlighting how calibration significantly improves...