For the purpose of selecting the best explaining variables of Grey system and ensuring that the explaining variables can represent most information of original data,the paper presents a new combination forecasting method,which combines Chief Component Analysis method with Grey System Theory.

The proper method of thought may give good instruction to scientific research,inference to the best explanation is one of the important ones.

Taking the undertaking investment cost for a public library and the number of the staff and readers in a public libraries as the explanatory variables, the paper tries to use a regression anlaysis method to set up a cost model for prefectural and municipal public libraries.

To design the explanatory variables in the early warning model effectively,125 industrial listed companies in China are investigated,according to the status of their equity structure and relevant laws,as well as the impact of equity struture variables on business f.