To reduce the number of variables or factors that do not know the value of a variable or group can be divided into small groups and given a factor group of variables, or variables that are most important as a RedX.
To reduce the number of variables or factors that do not know the value. By segmenting variables or factors in small groups. And assigned to the variable or variables that are most important RedX.
To reduce the number of variables or factors don't value. By grouping variables or factors in small groups. In order to variable or variables, the most important is RedX.