The problem is to get a high enough speed to break the atom entirely apart. In doing cold fusion there are some problems of disturbances. The radiation that was detected could have resulted from the presence of uranium in larger than average quantities in the ground beneath site where the experiment was conducted. In other words, randomiza tion is a particular way of controlling for effects of other variables. Necessity and Limitations of Randomization .
Randomization is at the heart of experimental design.
They are properly called quasi-experimental designs. The text says that experimental and control groups should be alike in all respects save treatment and that there are several ways to achieve such comparability. Randomization is one of them, but probability sampling and matching are suggested as others. Probability sampling is equivalent to random assignment. Taking two random samples from a population is the same as taking one larger sample randomly and then assigning the members of the sample to two groups.