- The average of guesses of a large number of people will typically be more accurate than an individual can be - (wisdom of crowds) - Bootstrapping - generates simulated samples by sampling with replacement from existing sample - sampling is random - Out of bag sample - data that was never picked in bootstrapping - is often used for testing data (OOB samples were not in the training samples so the model has never seen them) - with common techniques often ~30% of data is not picked (and forms OOB set) - distribution of classes with bootstrapping will form a Gaussian distribution - when enough samples are used bootstrap distributions will approximate population statistics - Assumption is made with bootstrapping that the sample approximates the original population - bootstrap samples are used as training sets, OOB samples serve as testing sets ```python bootstrap_samples = [resample(df, replace=True, random_state=i) for i in range(5)] ```