The main purpose of redundant variable test is to check whether there are unnecessary or redundant variables in the model. These redundant variables may affect the accuracy and efficiency of the model, because they may not provide any new information. If there are redundant variables, the existence of these variables may lead to the efficiency loss of regression coefficient estimation. Therefore, through the inspection of redundant variables, we can determine which variables are redundant, so that we can delete these redundant variables and improve the accuracy and efficiency of the model.

Cyclic Redundancy Check (CRC) is a hash function that generates short fixed-digit check codes based on online data packets or computer files, and is mainly used to detect or check possible errors after data transmission or storage. The generated numbers are calculated and appended to the data before transmission or storage, and then the receiver checks to determine whether the data has changed.

Generally speaking, the value of cyclic redundancy check is a 32-bit integer. This function is widely used because it is easy to use binary computer hardware, easy to perform mathematical analysis, and especially good at detecting errors caused by transmission channel interference. This method was published by W. Wesley Peterson in 196 1