Mary Hall is a editor for Investopedia's Advisor Insights, in addition to being the editor of several books and doctoral papers. Mary received her bachelor's in English from Kent State University with ...

Melissa Horton is a financial literacy professional. She has 10+ years of experience in the financial services and planning industry. Robert Kelly is managing director of XTS Energy LLC, and has more ...

Understanding the differences between convenience, target, and self-selected samples. Representative samples and sampling are addressed multiple times in the cGMPs. For example, in Part 21 of the Code ...