Wondering how many people in the United States have a smartphone? If you poll 20 people on the street, your survey won’t be representative of the entire American population. But if you just want to ...

Learn the distinctions between simple and stratified random sampling. Understand how researchers use these methods to accurately represent data populations.

Recent studies have demonstrated that principal component analysis (PCA) can detect the presence of population mixture and admixture in a sample and thus can be used to correct population ...