<P> Random sampling is a related, but distinct process . Random sampling is recruiting participants in a way that they represent a larger population . Because most basic statistical tests require the hypothesis of an independent randomly sampled population, random assignment is the desired assignment method because it provides control for all attributes of the members of the samples--in contrast to matching on only one or more variables--and provides the mathematical basis for estimating the likelihood of group equivalence for characteristics one is interested in, both for pretreatment checks on equivalence and the evaluation of post treatment results using inferential statistics . More advanced statistical modeling can be used to adapt the inference to the sampling method . </P> <P> Randomization was emphasized in the theory of statistical inference of Charles S. Peirce in "Illustrations of the Logic of Science" (1877--1878) and "A Theory of Probable Inference" (1883). Peirce applied randomization in the Peirce - Jastrow experiment on weight perception . </P> <P> Charles S. Peirce randomly assigned volunteers to a blinded, repeated - measures design to evaluate their ability to discriminate weights . Peirce's experiment inspired other researchers in psychology and education, which developed a research tradition of randomized experiments in laboratories and specialized textbooks in the eighteen - hundreds . </P> <P> Jerzy Neyman advocated randomization in survey sampling (1934) and in experiments (1923). Ronald A. Fisher advocated randomization in his book on experimental design (1935). </P>

What types of conclusions can be drawn from random assignment and random sampling