Book Image

Data Cleaning and Exploration with Machine Learning

By : Michael Walker
Book Image

Data Cleaning and Exploration with Machine Learning

By: Michael Walker

Overview of this book

Many individuals who know how to run machine learning algorithms do not have a good sense of the statistical assumptions they make and how to match the properties of the data to the algorithm for the best results. As you start with this book, models are carefully chosen to help you grasp the underlying data, including in-feature importance and correlation, and the distribution of features and targets. The first two parts of the book introduce you to techniques for preparing data for ML algorithms, without being bashful about using some ML techniques for data cleaning, including anomaly detection and feature selection. The book then helps you apply that knowledge to a wide variety of ML tasks. You’ll gain an understanding of popular supervised and unsupervised algorithms, how to prepare data for them, and how to evaluate them. Next, you’ll build models and understand the relationships in your data, as well as perform cleaning and exploration tasks with that data. You’ll make quick progress in studying the distribution of variables, identifying anomalies, and examining bivariate relationships, as you focus more on the accuracy of predictions in this book. By the end of this book, you’ll be able to deal with complex data problems using unsupervised ML algorithms like principal component analysis and k-means clustering.
Table of Contents (23 chapters)
1
Section 1 – Data Cleaning and Machine Learning Algorithms
5
Section 2 – Preprocessing, Feature Selection, and Sampling
9
Section 3 – Modeling Continuous Targets with Supervised Learning
13
Section 4 – Modeling Dichotomous and Multiclass Targets with Supervised Learning
19
Section 5 – Clustering and Dimensionality Reduction with Unsupervised Learning

K-nearest neighbors regression

As mentioned previously, K-nearest neighbors can be a good alternative to linear regression when the assumptions of ordinary least squares do not hold, and the number of observations and dimensions is small. It is also very easy to specify, so even if we do not use it for our final model, it can be valuable for diagnostic purposes.

In this section, we will use KNN to build a model of the ratio of female to male incomes at the level of country. We will base this on labor force participation rates, educational attainment, teenage birth frequency, and female participation in politics at the highest level. This is a good dataset to experiment with because the small sample size and feature space mean that it is not likely to tax your system’s resources. The small number of features also makes it easier to interpret. The drawback is that it might be hard to find significant results. That being said, let’s see what we find.

Note

We will...