What are three principles of fair testing?

1. Control: All variables other than the independent variable should be kept constant. This means that any differences in the results can be attributed to the independent variable.

2. Randomization: Participants in the experiment should be randomly assigned to the different groups or conditions. This helps to ensure that any differences in the results are not due to other factors, such as the characteristics of the participants.

3. Blinding: The participants and the researchers should be blind to the group or condition that each participant is in. This helps to prevent any bias from affecting the results.