## 3 Results and Discussion
### Determination of Factor Analysis Methods  
In our study, through the comparison of filter-based and wrapper-based feature extraction methods, the RFE method is used to analyze the factors that affect market demands of three kinds of excavators. The main indexes are listed in Table 3.  
According to results, the factor labels for each kind of excavator are listed in Table 4.  
From the decomposition results, it can be seen that the influencing factors for different kinds of excavators are different, and there are great differences among the medium-sized excavators. According to market demand factors, large excavators are mainly used in mining, which has a relatively single application scenario. Similarly, as for the small excavators, which applications include municipal construction, residential construction, etc. The limitation of the applications makes factor labels of both large-sized and small-sized less than the medium ones.  
On the other hand, for medium-sized excavators, the wide range of applications makes its influencing factors of demand complicated and diverse, and it is difficult to describe it with fewer factors.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Types** & \multicolumn{2}{c}{**Factor Labels**} \\ \hline Large & \multicolumn{2}{c}{(8) (96) (102) (108) (109) (110)} \\ Medium & (9) (10) (16) (24) (32) (38) (40) (84) (88) (91) (94) (101) (106) (107) (109) (110) \\ Small & \multicolumn{2}{c}{(4) (41) (49) (53) (106)} \\ \hline \hline \end{tabular}
\end{table}
Table 4: Feature ranking of different types of excavator’s market capacity.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Significance Ordering** & **Large** & **Medium** & **Small** \\ \hline
1 & Previous Demand of Medium & Previous Demand of Medium & Previous Demand of Small \\  & Excavator & Excavator & Excavator \\ \hline
2 & Six-month Interest Rate on & Cash in Circulation Supply & Current Value of Total \\  & Bank Loans & Bank Loans & End Value (M0) & Investment in Real Estate \\  & & & Development Plan \\ \hline
3 & Previous Total Demand of & Previous Demand of Small & Current Value of Natural Gas \\  & Excavators & Excavators & Production \\ \hline
4 & Previous Demand of Large & \multicolumn{2}{c}{} \\  & Excavators & Loan for Six Months & Current Value of Investment \\  & Excavators & Loan for Six Months & in Fixed Assets of Ferrous \\  & Excavators & & Metal Mining and Dressing \\ \hline
5 & Current Value of Luxury & \multicolumn{2}{c}{} \\  & Retail & \multicolumn{2}{c}{} \\  & & \multicolumn{2}{c}{} \\  & & \multicolumn{2}{c}{} \\ \end{tabular} \
\begin{tabular}{c} Current Value of Investment \\ in Fixed Assets of Public \\ Facilities Management \\ Industry \\ \end{tabular} &
\begin{tabular}{c} Current Value of Investment \\ in Fixed Assets of Public \\ Construction Industry \\ \end{tabular} \\ \hline
6 & Bank Deposit Interest Rate & Current Value of Real Estate & / \\  & (Demand) & Land Acquisition Costs & / \\ \hline
1 & \multicolumn{2}{c}{} \\ \end{tabular}
\end{table}
Table 3: Feature ranking of different types of excavators’ market capacity.  
According to the results of the indicators, the market demand is closely related to the real estate industry, water conservancy projects, environmental management, public management, transportation, and the cash supply and loan factors in circulation in the financial industry. At the same time, it is interesting to note that the market demand of all types of excavators is strongly related to their previous sales and the sales of the excavators with slightly smaller tonnage.