Investopedia contributors come from a range of backgrounds, and over 25 years there have been thousands of expert writers and editors who have contributed. Representative sampling and random sampling ...

Julie Young is an experienced financial writer and editor. She specializes in financial analysis in capital planning and investment management. Dr. JeFreda R. Brown is a financial consultant, ...

Note: This report was updated on Dec. 30, 2015 to reflect the January-July 2015 National Health Interview Survey estimates released on December 1, 2015. Telephone surveys face numerous challenges, but ...

Improving reproducibility and transparency in science requires increased attention to the details of research. We have previously reported that studies citing the inability to replicate findings in ...

PROC SURVEYSELECT provides a variety of methods for selecting probability-based random samples. With probability sampling, each unit in the survey population has a known, positive probablity of ...

The rise of internet polling makes it more feasible to publish estimates for Asian Americans. But these estimates offer a limited view. What does the migration to online polling mean for the country’s ...

Scientists at the National Institutes of Health (NIH) have developed a new sample preparation method to detect SARS-Cov-2, the virus that causes COVID-19. The method bypasses extraction of the virus’ ...

Quantitative research relies on analyzing statistical data, while qualitative research focuses on answering important business questions, including discovering why customers select products or ...

Single-cell proteomics provides information about a cell at its protein level, which can prove useful for anticancer drug resistance and cell differentiation research. However, current proteomics ...