为什么aggregation不行呢

问题如下：

During the preprocessing of the data in Exhibit 1, what type of data transformation did Steele perform during the data preprocessing step?

选项：

Extraction

Conversion

Aggregation

解释：

A is correct. During the data preprocessing step, Steele created a new “Age” variable based on the firm’s IPO date and then deleted the “IPO Date” variable from the dataset. She also created a new “Interest Coverage Ratio” variable equal to EBIT divided by interest expense. Extraction refers to a data transformation where a new variable is extracted from a current variable for ease of analyzing and using for training an ML model, such as creating an age variable from a date variable or a ratio variable. Steele also performed a selection transformation by deleting the IPO Date variable, which refers to deleting the data columns that are not needed for the project.