Note: If more than $13,000 of debt is canceled in one year, the gift giver has to file a gift tax return (although they almost certainly will not owe a tax). That should not affect you as the recipient. Example: Roxy borrowed $6,000 from her dad while she was unemployed. She wrote up a promissory note for the debt.
Control Group and Experimental Group. True experiments must have a control group, which is a group of research participants that resemble the experimental group but do not receive the experimental treatment. The control group provides a reliable baseline data to which you can compare the experimental results.
Control groups are an important part of many scientific experiments. Researchers use control groups to find out if a treatment really has an effect. Sometimes, study subjects act differently after treatment just because they know they got treated. For example, imagine this scene. You go to your doctor and tell her that you can't sleep at night.