Randomization is the process of making something random. Randomization is not haphazard; instead, a random process is a sequence of random variables describing a process whose outcomes do not follow a deterministic pattern, but follow an evolution described by probability distributions. For example, a random sample of individuals from a population refers to a sample where every individual has a known probability of being sampled. This would be contrasted with nonprobability sampling where arbitrary individuals are selected.

In various contexts, randomization may involve:

• generating a random permutation of a sequence (such as when shuffling cards);
• selecting a random sample of a population (important in statistical sampling);
• allocating experimental units via random assignment to a treatment or control condition;
• generating random numbers (random number generation); or
• transforming a data stream (such as when using a scrambler in telecommunications).