2. The main task of secondary coding (also known as axial coding) is to find and establish various relationships between concept categories, so as to show the organic relationships between various parts of data. These relationships can be causal, sequential, semantic, situational, similarity, difference, equivalence, type, structure, function, process, strategy and so on. In axis login, researchers only make in-depth analysis of one generality at a time, and look for relevant relationships around this generality, so it is called "axis".
3. Three-level coding (also called selective coding) refers to selecting a "core category" from all discovered concept categories after systematic analysis, and the analysis constantly focuses on those code numbers related to the core category. The core genus must be proved to be dominant again and again in comparison with other genera, and the most research results can be included in a broader theoretical scope.