It depends on the purpose and object of the study. Generally speaking, grouping subjects by age can better explore and analyze the characteristics, needs and development trends of people of different age groups. If the graduation thesis studies the consumption behavior of a certain age group, then the topics can be grouped according to different age groups, such as 18-24 years old, 25-34 years old, 35-44 years old and so on. The research objects are students or professionals of a certain age, and they can also be grouped according to different age groups, such as 18-22 years old, 23-28 years old, 29-35 years old and so on.