1) implicit factor
2) danger factors
3) invisible factors
When referring to the problems of urban traffic, visible factors including the construction of road transportation equipment, establishment of traffic law and the degree of executing law are concerned, whereas invisible factors such as construction of culture are neglected.
4) concealed factors
This paper uses the priority factor method to analyses the status of many factors correlated with the purchases of houses,accordingly discusses the concealed factors of inordinately zooming house price,which perhaps offers the theoretical reference for the purchase of houses in choosing house and restraining price.
5) implicit elements
6) Quantity of implicit factors