Devoting my time to deeply understanding a subject of my interest has long been a dream since I was a kid. I consider myself very fortunate to have such a chance to pursue economic research toward the PhD at West Virginia University. Indeed, this dream becomes true as a result of tremendous help and supports from the most important people in my life. First of all, it is my genuine pleasure to express my deep gratitude to my advisor, Dr. Feng Yao, who has consistently provided generous help to my research. Without the clear guidance and inspiration from Dr. Yao, it is impossible for me to conduct my initial research in Nonparametric Econometrics. Dr. Yao always possesses enthusiastic attitude towards research works, which greatly encourages me to face and solve challenging works throughout the research process. With detailed explanation by Dr. Yao on technical issues, I am able to go deeper in the field of Econometrics, and see many interesting and promising topics for my future works. I would like to extend my gratitude to my committee members, Dr. Arabinda Basistha, Dr. Jane Resuske, and Dr. Xiaoli Etienne, for their constructive feedbacks and advices on my present studies. I also gratefully thank Dr. Guillermo Franco for his generous help on High Performance Computing, which significantly facilitates many of my projects. Last of all, I greatly thank my mother Yihong Zhang for her endless love throughout my life, and my loving fiancé Jinjing Tian for her invaluable support to my PhD life and inspiration for my research. I also thank my best friend, Tingyu Li, who always have a way to cheer me up when I face obstacles. iii Exploration and abstention of coal and char industry Exploration of oil and natural gas industry