Book Image

Data Analysis with R, Second Edition - Second Edition

Book Image

Data Analysis with R, Second Edition - Second Edition

Overview of this book

Frequently the tool of choice for academics, R has spread deep into the private sector and can be found in the production pipelines at some of the most advanced and successful enterprises. The power and domain-specificity of R allows the user to express complex analytics easily, quickly, and succinctly. Starting with the basics of R and statistical reasoning, this book dives into advanced predictive analytics, showing how to apply those techniques to real-world data though with real-world examples. Packed with engaging problems and exercises, this book begins with a review of R and its syntax with packages like Rcpp, ggplot2, and dplyr. From there, get to grips with the fundamentals of applied statistics and build on this knowledge to perform sophisticated and powerful analytics. Solve the difficulties relating to performing data analysis in practice and find solutions to working with messy data, large data, communicating results, and facilitating reproducibility. This book is engineered to be an invaluable resource through many stages of anyone’s career as a data analyst.
Table of Contents (24 chapters)
Title Page
Copyright and Credits
Packt Upsell
Contributors
Preface
Index

A one-sample test of means


We finally have enough knowledge under our belts to perform a null-hypothesis significance test using the bootstrap. In fact, given what we already learned, it can scarcely be easier!

As a note, I prefer to use the the bootstrap mainly as a method of generating confidence intervals and illustrating uncertainty in population parameter estimates, and not as a tool for NHST. But, at least as a demonstration, we'll see a few examples of it being used for hypothesis testing here.

For ease of comparison, let's repeat the one sample test that we performed in Chapter 6, Testing Hypotheses. Recall, that the precip built-in dataset contained the precipitation (in inches) of a sample of US cities. We wanted to know if the mean of the population US precipitation was significantly discrepant from the precipitation average of the rest of the world – a value that we, quite unjustifiably, and arbitrarily, said to be 38 inches.

The one sample t-test was performed thusly:

> t.test...