Book Image

Machine Learning with R - Fourth Edition

By : Brett Lantz
5 (1)
Book Image

Machine Learning with R - Fourth Edition

5 (1)
By: Brett Lantz

Overview of this book

Dive into R with this data science guide on machine learning (ML). Machine Learning with R, Fourth Edition, takes you through classification methods like nearest neighbor and Naive Bayes and regression modeling, from simple linear to logistic. Dive into practical deep learning with neural networks and support vector machines and unearth valuable insights from complex data sets with market basket analysis. Learn how to unlock hidden patterns within your data using k-means clustering. With three new chapters on data, you’ll hone your skills in advanced data preparation, mastering feature engineering, and tackling challenging data scenarios. This book helps you conquer high-dimensionality, sparsity, and imbalanced data with confidence. Navigate the complexities of big data with ease, harnessing the power of parallel computing and leveraging GPU resources for faster insights. Elevate your understanding of model performance evaluation, moving beyond accuracy metrics. With a new chapter on building better learners, you’ll pick up techniques that top teams use to improve model performance with ensemble methods and innovative model stacking and blending techniques. Machine Learning with R, Fourth Edition, equips you with the tools and knowledge to tackle even the most formidable data challenges. Unlock the full potential of machine learning and become a true master of the craft.
Table of Contents (18 chapters)
16
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17
Index

Measuring performance for classification

In the previous chapters, we measured classifier accuracy by dividing the number of correct predictions by the total number of predictions. This finds the proportion of cases in which the learner is correct, and the proportion of incorrect cases follows directly. For example, suppose that a classifier correctly predicted whether newborn babies were a carrier of a treatable but potentially fatal genetic defect in 99,990 out of 100,000 cases. This would imply an accuracy of 99.99 percent and an error rate of only 0.01 percent.

At first glance, this appears to be an extremely valuable classifier. However, it would be wise to collect additional information before trusting a child’s life to the test. What if the genetic defect is found in only 10 out of every 100,000 babies? A test that invariably predicts no defect will be correct for 99.99 percent of all cases, but incorrect for 100 percent of the cases that matter most. In other words...