Answer:
Repeatable with Randomly picked subjects.
Step-by-step explanation:
There are some characteristics of good experimental design. On this matter, we'll work with Statistics. Firstly, the Sample Group, for a matter of economy and deadline we'll work with sample groups. It must be randomly taken following valid statistical parameters, to assure its validity. In addition to this, its control group must be tested and therefore be valid for the experiment.
Finally, the subjects or individuals must be randomly chosen, so that, every time the experience runs either on the control or the experimental group.