Missing Value Treatment – Mean, Median, Mode, KNN Imputation, and Prediction
Missing Value treatment is no doubt one of the most important parts of the whole process of building a model. Why?
Because we can’t afford to eliminate rows wherever there is a missing value in any of the columns. We need to tackle it in the best possible way. There are multiple ways to deal with missing values, and these are my top four methods:-
1. Mean – When do you take an average of a column? There is a saying which goes like this, “When a Billionaire walks in a small bar, everyone becomes a millionaire”
So, avoid using Mean as a missing value treatment technique when the range is too high. Suppose there are 10,000 employees with a salary of Rs.40,000 each and there are 100 employees with a salary of Rs. 1,00,000 each. In this case you can consider using the mean for missing value treatment.
But, if there are 10 employees with 8 employees earning Rs.40,000 and one of them earning Rs. 10,00,00. Now, here you should avoid using mean for missing value treatment. You can use mode !!
2. Median – Median is the middle term when you write the terms in ascending or descending order. Think of one example where you can use this? The answer is at the bottom of the article
3. Mode – Mode is the maximum occurring number. As we discussed in point one, we can use Mode where there is a high chance of repetition.
4. KNN Imputation – This is the best way to solve a missing value, here n number of similar neighbors are searched. The similarity of two attributes is determined using a distance function.
In one of the Hackathon, I had to impute or treat the missing value of age, so I tried the following way out( in R)
new_dataset <- knnImputation(data = df,k=8)
k-nearest neighbour can predict both qualitative & quantitative attributes but it consumes a lot of time and processor
x <- ts(c(12,23,41,52,NA,71,83,97,108))
na.interpolation(x, option = “spline”)
na.interpolation(x, option = “stine”)
5. Bonus type – Prediction
This is another way of fixing the missing values. You can try linear regression/time series analysis or any other method to fill in the missing values using prediction
Median – You can use median where there is low variance in age
Came across KNN Imputation, so thought of sharing the same !!
Keep Learning 🙂
The Data Monk