1. Learn
    2. /
  2. Courses
    3. /
  3. Handling Missing Data with Imputations in R
  • 1

    The Problem of Missing Data

    Free

    In this chapter, you’ll find out why missing data can be a risk when analyzing a dataset. You’ll be introduced to the three missing data mechanisms and learn how to recognize them using statistical tests and visualization tools.

  • 2

    Donor-Based Imputation

    Get to know the taxonomy of imputation methods and learn three donor-based techniques: mean, hot-deck, and k-Nearest-Neighbors imputation. You’ll look under the hood to see how these methods work, before learning how to apply them to a real-world tropical weather dataset. Along the way, you’ll also learn useful tricks that you can use to make them work even better for your problems.

  • 3

    Model-Based Imputation

    It’s time to learn how to use statistical and machine learning models, such as linear regression, logistic regression, and random forests, to impute missing data. In this chapter, you’ll look into how the models make their predictions and use this knowledge to draw the imputed values from conditional distributions. This is important as it ensures your imputations are more varied and plausible, making them more similar to the true data.

  • 4

    Uncertainty from Imputation

    Imputed values are not set in stone. They are just estimates and estimates come with some uncertainty. In this final chapter, you’ll discover how bootstrapping and chained equation using the mice package can be used to incorporate imputation uncertainty into your models and analyses to make them more reliable and robust.

Initializing

Exercise

Imputing with random forests

A machine learning approach to imputation might be both more accurate and easier to implement compared to traditional statistical models. First, it doesn't require you to specify relationships between variables. Moreover, machine learning models such as random forests are able to discover highly complex, non-linear relations and exploit them to predict missing values.

In this exercise, you will get acquainted with the missForest package, which builds a separate random forest to predict missing values for each variable, one by one. You will call the imputing function on the biographic movies data, biopics, which you have worked with earlier in the course and then extract the filled-in data as well as the estimated imputation errors.

Let's plant some random forests!

Instructions

100 XP
  • Load the missForest package.
  • Use missForest() to impute missing values in the biopicsdata; assign the result to imp_res.
  • Extract the imputed data set from imp_res, assign it to imp_data, and check if the number of missing values is indeed zero.
  • Extract the estimated imputation error from imp_res, assign it to imp_err, and print it to the console.