Final answer:
Test methods are in control when the control group is identical to the experimental group except for the one variable being tested, thereby enabling a fair comparison between groups that differ in only that one independent variable.
Step-by-step explanation:
Test methods are considered in control when two key conditions are met:
- The control group must be identical to the test group except for the one variable being tested.
- This allows for a comparison between groups that are different in only one independent variable.
For instance, if scientists are testing the efficacy of a new drug, they will have an experimental group that receives the drug and a control group that does not. Both groups should be kept as similar as possible, with the only difference being the administration of the drug to the experimental group. By comparing the outcomes between the two, researchers can deduce if the drug has an effect.