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Hands-On Ensemble Learning with R

You're reading from  Hands-On Ensemble Learning with R

Product type Book
Published in Jul 2018
Publisher Packt
ISBN-13 9781788624145
Pages 376 pages
Edition 1st Edition
Languages
Author (1):
Prabhanjan Narayanachar Tattar Prabhanjan Narayanachar Tattar
Profile icon Prabhanjan Narayanachar Tattar
Toc

Table of Contents (17) Chapters close

Hands-On Ensemble Learning with R
Contributors
Preface
1. Introduction to Ensemble Techniques 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?
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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