The master's thesis can't study the main effect of intermediary effect, because it can only show that no intermediary effect is found in the current sample. There are many reasons, that is, there is no intermediary effect, and statistical test is not enough to find the intermediary effect (which is already there). So there is no intermediary effect when it is not significant.

Simply put, when a conclusion is reached, a series of methods are needed to verify whether the conclusion is reliable. When certain conditions change or the conclusion is assumed to remain unchanged, then the conclusion is robust and debatable. It is necessary to find out the reason for the change and explain it.

Intermediate variable:

Mediator is an important statistical concept. If the independent variable X has a certain influence on the dependent variable Y through a certain variable M, then M is called the intermediary variable of X and Y. The purpose of studying the intermediary is to explore the internal mechanism of this relationship on the basis of understanding the relationship between X and Y.

In this process, the original research on the same phenomenon can be linked, and the original theories used to explain similar phenomena can be integrated to make the existing theories more systematic. The study of intermediary variables can not only explain the mechanism behind the relationship, but also integrate the existing research or theory, which is of great theoretical and practical significance.

Reference to the above content: Baidu Encyclopedia-Master thesis