do you mean a hypothesis?
if so it's like what you think will happen..
pretty much like a prediction
One way to test a hypothesis is through a controlled experiment, where an independent variable is manipulated while keeping all other variables constant. This allows researchers to observe the effects of the manipulation on a dependent variable, thereby establishing a cause-and-effect relationship. By comparing the results between a control group and an experimental group, researchers can determine whether the hypothesis is supported or refuted.
His experiment supplied evidence that DNA is not the genetic material by showing that the activity of the material responsible for transformation was not affected by protein-destroying enzymes, but was destroyed when a DNA-destroying enzyme was present. Cristian Mendoza 11/1/12