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 ...

Genome-wide association (GWA) studies are an effective approach for identifying genetic variants associated with disease risk. GWA studies can be confounded by population stratification — systematic ...

Most medicines are currently prescribed empirically. Some work for almost all relevant patients, such as non-steroidal anti-inflammatory drugs (NSAIDs) for pain relief, the proton-pump inhibitors ...

Prior to the 20 th Century, one of the most common ways of seeing the world was through the lens of stratification, which is the idea that the natural world comes in different scales or layers. For ...

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, ...