The advantage of using a random process to establish groups is that it is fair and unbiased. Just as football reams use a coin toss to determine who receives the opening kickoff, random assignment eliminates prejudice from the decision process. However, a random process does not guarantee a perfectly balanced outcome. When tossing a coin, for example, we can expect an equal, “50-50,” distribution of heads and tails in the long run (with a large sample). However, in the short run (with a small sample), there are no guarantees. A sample of only n = 10 tosses, for example, can easily contain eight or nine heads and only one or two tails. With any random process, we trust chance to create a balanced outcome. In the long run, chance proves to be fair, but in the short run, anything can happen by chance. Specifically, there is always a possibility that random assignment will produce groups that have different characteristics and thus confound the experiment. Because pure chance is not a dependable process for obtaining balanced and equivalent groups, researchers often modify random processes by placing some limitations on or exerting some control over the outcomes. One such modification, restriction of equal group sizes, has been discussed; two additional techniques follow.