Why would a scientist need to identify variables?

Variables are the basis of a scientific experiment. When the scientist is carrying out his procedure, he is actually altering a variable, called the independent variable. Unless he just likes playing with chemicals, he is likely attempting to get a result, and he does this by using measurements of the dependent variable, which has changed because of the manipulation of the independent variable. Identifying the variables becomes very important when formulating more complicated studies, and becomes the bread and butter of psychological experiments.