Hi,everyone~ I'm just beginner of bootstrapping method and I got some reply saying that bigger data usually has better result. Thank you again for the answer. My question is if do we have all data - population don't we need to care about the distribution when we calculate standard variance, confidence interval things like that? Many thanks! best regard, ~~~~~~~~~~~~~~~~~ Yongkyu Shin Office Water Resource CSUS Civil Eng. ~~~~~~~~~~~~~~~~~ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%