英语翻译
文章主要是讲social media data的优缺点当其用在科学研究中的时候.讲缺点的时候有这样一句话：We will begin by talking about sampling problems.A sampling frame is often impossible to creat.Except in certain limited circumstances it is possible to get a definitive list of email addresses,web pages,etc.This means that no unbiased sample is possible and most samples using NSM are convienience samples.