Learn how representative samples and random samples differ and why combining them minimizes sampling bias for accurate data.

Sampling allows archaeologists to draw conclusions about a site or region using only a fraction of the area. Because excavation is destructive and funding is limited, leaving parts unexcavated can be ...

Suppose that the sample of students described in the previous section was actually selected using stratified random sampling. In stratified sampling, the study population is divided into ...

Producers of infant formula employ comprehensive food safety systems, including product testing to ensure those systems are working. A new study from the University of Illinois Urbana-Champaign finds ...

Several states with extensive water use databases rely upon the census approach. That is, data are collected for all water users withdrawing amounts greater than a specified threshold that varies from ...

In a recently published news story, we learn about a young doctor, Jake Deutsch, and his personal experience with coronavirus disease 2019. Deutsch tested positive for Covid-19 and checked himself ...

Suppose that the previous student sample is actually drawn from a stratified sampling. The strata are grades in the junior high school: the 7th grade, the 8th grade, and the 9th grade. Within strata, ...