Snedecor, G. W. (1938). An experiment designed to compare measurements of individuals. In G. W. Snedecor, Statistical methods: Applied to experiments in agriculture and biology (pp. 25-45). Ames, IA, US: Collegiate Press.
http://dx.doi.org/10.1037/13503-002
In the first chapter (see record 2008-15885-001) only one kind of data was considered, that resulting from the enumeration of individuals possessed of some interesting attribute. Life or death, infested or free, red or white-such were the categories observed. Another type of data, even more common, derives from measuring some continuous variate like height or yield. How much do you weigh? How old are you? Numerical facts like these are intimately related to all our thinking. In this and following chapters will be developed statistical methods appropriate to such measurement data. One of the simplest of experiments, as well as a most effective one, may be planned to contrast the behavior of two similar individuals under different experimental conditions. The individuals to be compared may be field plots or pigs or colonies of bees. The pairs are replicated, one member of every pair receiving the first treatment, the other member the second. Let us examine the circumstances under which such an experiment is set up, together with the statistical method for reducing the data. (PsycINFO Database Record (c) 2016 APA, all rights reserved)