An experiment is a study in which treatments are given in order to determine their effects. For instance, one group of students might be trained to use conflict-resolution techniques while a control group is not given any training. Then, the students in both groups could be observed on the playground to determine whether the experimental group uses more conflict-resolution techniques than the control group. Random assignment to two groups in the experiment on conflict-resolution training would provide assurance that there is no bias, such as systematically assigning the less-aggressive children to the experimental group. Researchers often rely on other individuals, such as graduate assistants, teachers, and psychologists, to administer the treatments they use in experiments. If participants have no knowledge of whether they are in the experimental or control group, such experiments are called blind, or blinded.