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Sep. 20, 2017
Jan. 18, 2017

bootstrapped - confidence intervals made easy

bootstrapped is a Python library that allows you to build confidence intervals from data. This is useful in a variety of contexts - including during ad-hoc a/b test analysis.

bootstrapped - Benefits

  • Efficient computation of percentile based confidence intervals
  • Functions to handle single populations and a/b test scenarios
  • Functions to understand statistical power

Example Usage

import numpy as np
import bootstrapped.bootstrap as bs
import bootstrapped.stats_functions as bs_stats

mean = 100
stdev = 10

population = np.random.normal(loc=mean, scale=stdev, size=50000)

# take 1k 'samples' from the larger population
samples = population[:1000]

print(bs.bootstrap(samples, stat_func=bs_stats.mean))
>> 100.08  (99.46, 100.69)

print(bs.bootstrap(samples, stat_func=bs_stats.std))
>> 9.49  (9.92, 10.36)

Extended Examples


bootstrapped requires numpy and pandas. The power analysis plotting function requires matplotlib. statsmodels is used in some of the examples.


# clone bootstrapped 
cd bootstrapped 
pip install -r requirements.txt 
python install

How bootstrapped works

tldr - Percentile based confidence intervals based on bootstrap re-sampling with replacement.

Bootstrapped generates confidence intervals given input data by:

  • Generating a large number of samples from the input (re-sampling)
  • For each re-sample, calculate the mean (or whatever statistic you care about)
  • Of these results, calculate the 2.5th and 97.5 percentiles (default range)
  • Use this as the 95% confidence interval

For more information please see:

  1. Bootstrap confidence intervals (good intro)
  2. An introduction to Bootstrap Methods
  3. When the bootstrap dosen't work
  4. (book) An Introduction to the Bootstrap
  5. (book) Bootstrap Methods and their Application

See the CONTRIBUTING file for how to help out.


Spencer Beecher, Don van der Drift, David Martin, Lindsay Vass, Sergey Goder, Benedict Lim, and Matt Langner.

Special thanks to Eytan Bakshy.


bootstrapped is BSD-licensed. We also provide an additional patent grant.

Latest Releases
 May. 29 2017
 May. 29 2017