What is the main concern$/$purpose of Statistical Process Control $($SPC$)$ and Statistical Quality Control $($SQC$)?$ Select two $(2)$ statements that apply.

It is concerned with checking data on reports for corporate personnel.

It is used to document recommendations from customers and to record the improvements where needed.

It is the application of statistical techniques to the output $($quality$)$ of a process.

It keeps track of a process in order to reduce variation of improve quality.