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Quantifying uncertainty using the bootstrap

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1 Quantifying uncertainty using the bootstrap
Reading Efron, B. and R. Tibishirani, (1993), An Introduction to the Bootstrap, Chapman Hall, New York, 436 p. Chapters 1, 2, 6.

2 Approaches to uncertainty estimation
Use statistical theory Bootstrapping e.g. Standard Error Confidence Intervals:

3 Bootstrapping Motivated by the absence of equations for other accuracy measures (bias, prediction error, confidence intervals) for statistics of interest (correlation, regressions, ACF) Definition: “The bootstrap is a data-based simulation method for statistical inference.” Principle: resample with replacement from data. After Efron and Tibshirani, An Introduction to the Bootstrap, 1993

4 from Efron and Tibshirani, An Introduction to the Bootstrap, 1993

5 Schematic of Bootstrap Process
from Efron and Tibshirani, An Introduction to the Bootstrap, 1993

6 Bootstrapping REAL WORLD BOOTSTRAP WORLD Sampling with replacement
F x = {x1, x2, …, xn} BOOTSTRAP WORLD F * x * = {x*1, x * 2, …, x *n} Empirical Distribution Bootstrap Sample Bootstrap Replication Unknown Probability Distribution Observed Random Sample Sampling with replacement Statistic of Interest After Efron and Tibshirani, An Introduction to the Bootstrap, 1993

7 from Efron and Tibshirani, An Introduction to the Bootstrap, 1993

8 Bootstrap Algorithm for Standard Error
from Efron and Tibshirani, An Introduction to the Bootstrap, 1993

9 95% CI and interquartile range from 500 bootstrap samples
Hillsborough River at Zephyr Hills, September flows Mean = 8621 mgal S = mgal N = 31 Uncertainty on estimates of the mean One and two standard errors 95% CI and interquartile range from 500 bootstrap samples Millions of gallons


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