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Hands-On Ensemble Learning with R

You're reading from   Hands-On Ensemble Learning with R A beginner's guide to combining the power of machine learning algorithms using ensemble techniques

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Product type Paperback
Published in Jul 2018
Publisher Packt
ISBN-13 9781788624145
Length 376 pages
Edition 1st Edition
Languages
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Author (1):
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Prabhanjan Narayanachar Tattar Prabhanjan Narayanachar Tattar
Author Profile Icon Prabhanjan Narayanachar Tattar
Prabhanjan Narayanachar Tattar
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Table of Contents (15) Chapters Close

Preface 1. Introduction to Ensemble Techniques FREE CHAPTER 2. Bootstrapping 3. Bagging 4. Random Forests 5. The Bare Bones Boosting Algorithms 6. Boosting Refinements 7. The General Ensemble Technique 8. Ensemble Diagnostics 9. Ensembling Regression Models 10. Ensembling Survival Models 11. Ensembling Time Series Models 12. What's Next?
A. Bibliography Index

Bootstrap and testing hypotheses

We begin the bootstrap hypothesis testing problems with the t-test to compare means and the F-test to compare variances. It is understood that, since we are assuming normal distribution for the two populations under comparison, the distributional properties of the test statistics are well known. To carry out the nonparametric bootstrap for the t-statistic based on the t-test, we first define the function, and then run the bootstrap function boot on the Galton dataset. The Galton dataset is available in the galton data.frame from the RSADBE package. The galton dataset consists of 928 pairs of observations, with the pair consisting of the height of the parent and the height of their child. First, we define the t2 function, load the Galton dataset, and run the boot function as the following unfolds:

> t2 <- function(data,i) {
+   p <- t.test(data[i,1],data[i,2],var.equal=TRUE)$statistic
+   p
+ }
> data(galton)
> gt <- boot(galton,t2,R=100...
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