Imputation (statistics)

Imputation is a way of filling in missing data. Let's say you're trying to figure out the height of people in a class. You don't have the height for one of the students, but you do know that most of the students are around the same height. To do imputation, you would fill in the missing value with the average height of the other students. That way, your data set is complete and you can continue looking into new patterns.