Abstract:

Saturation has become an important criterion to judge the quality of qualitative research and explain the rationality of sample size. This paper systematically and critically reviews the literature and introduces three types of saturation: theoretical saturation, thematical saturation and data saturation and points out that researchers should consider their own overall research design to decide which model to adopt. The paper also introduces three ways to record the process of saturation. Among them, the structural coding book is more suitable for recording deductive thematical saturation and data saturation. There are two types of saturation tables which are more suitable for recording a prior thematical saturation. The conceptual depth scale is particularly suitable for recording theoretical saturation. This paper points out that saturation is a process rather than an event. Quality rather than quantity is the key to understand saturation. Saturation itself should be a concrete methodology practice. Researchers should pay attention to the concept of saturation and make a clear statement of the process of achieving saturation, which can help to improve the standardization, transparency, quality and recognition of qualitative research.

Key words: theoretical saturation, thematical saturation, data saturation, operationalization