 For most distributions of formula_60 (but not Mammen's), this method assumes that the 'true' residual distribution is symmetric and can offer advantages over simple residual sampling for smaller sample sizes.Different forms are used for the random variable formula_59, such as

The block bootstrap is used when the data, or the errors in a model, are correlated.In this case, a simple case or residual resampling will fail, as it is not able to replicate the correlation in the data.