Learn how representative samples and random samples differ and why combining them minimizes sampling bias for accurate data.
Greg DePersio has 13+ years of professional experience in sales and SEO and 3+ years as a writer and editor. Robert Kelly is managing director of XTS Energy LLC, and has more than three decades of ...
primary - information that is collected first-hand, eg tallies, measurements and photographs secondary - information that someone else has previously collected and made available, eg on the internet ...
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