Liu Yulin: currently, publicly available information is limited, and it is not possible to confirm the author's nationality, dates of birth and death, or detailed academic background. According to the library's holdings, the work Social Statistics is classified under social sciences and is the only title by this author currently visible. As an interdisciplinary field between sociology and statistics, social statistics generally involves the design of social surveys, data collection and organization, and statistical description and inference, serving the quantitative analysis of social phenomena and social problems. The book's placement in the social sciences category suggests that its intended readers may include students and researchers in sociology, social work, and related fields. Because no other works or biographical details are recorded, it is difficult at present to judge the author's overall writing style or academic trajectory; based on the available information, Liu Yulin's contribution is mainly embodied in this textbook or research work, and its influence awaits corroboration from further materials.
