To understand Mean or Median Imputation, we need to first revise the concepts of Mean & Median. Then it would be easy for us to know why this is a widely used method for imputation and can easily identify its issues. We already studied the Missing Data and defined Imputation & its basics in previous articles. What is Mean? Mean is nothing but the arithmetic average of numbers. That is why it is also referred to as Average or Arithmetic Average. The process of finding average/mean is quite simple, we just add all the given values irrespective of the magnitude(+/-) and then divide the total sum by the no. of observations. Sum of all the observation Average/Mean = --------------------------------------- No. of Observations