Book Image

R Statistics Cookbook

By : Francisco Juretig
2 (2)
Book Image

R Statistics Cookbook

2 (2)
By: Francisco Juretig

Overview of this book

R is a popular programming language for developing statistical software. This book will be a useful guide to solving common and not-so-common challenges in statistics. With this book, you'll be equipped to confidently perform essential statistical procedures across your organization with the help of cutting-edge statistical tools. You'll start by implementing data modeling, data analysis, and machine learning to solve real-world problems. You'll then understand how to work with nonparametric methods, mixed effects models, and hidden Markov models. This book contains recipes that will guide you in performing univariate and multivariate hypothesis tests, several regression techniques, and using robust techniques to minimize the impact of outliers in data.You'll also learn how to use the caret package for performing machine learning in R. Furthermore, this book will help you understand how to interpret charts and plots to get insights for better decision making. By the end of this book, you will be able to apply your skills to statistical computations using R 3.5. You will also become well-versed with a wide array of statistical techniques in R that are extensively used in the data science industry.
Table of Contents (12 chapters)

Choosing the best linear mixed model

When using OLS models, choosing the best one is not a complex task: we have a set of variables that we use, and we just pick whichever model has the lowest Akaike information criterion (AIC) (or any other appropriate metric that we choose).

Mixed models entail an extra level of complexity, as we can define the random effects in many ways. Resuming our previous example of deal_size versus time_spent and salespeople, we could choose a model with random effects only for the deal_size or both the deal_size and salespeople. We can also decide to add a random intercept or not, and we can force the model to assume that the shocks impacting each one of these are either, uncorrelated or correlated.

Choosing models by comparing the AIC is quite hard for mixed models, since we have a random and a fixed part. There are two types of analysis that we might...