Chapter two discusses research methods. All scientific research involves a variable, which is something that can take on value - variables can be both manipulated and measured. A variable is a characteristic person, place, or thing that can vary (is changeable) over time; some examples includes height, weight, etc. (powell, 51). When experimenting, it is often important to include both an independent and a dependent variable to show how the change in one variable may or may not affect the other variable. During the experiment, the independent variable varies when subject to the different conditions. The independent variable is manipulated throughout the experiment. On the other hand, the dependent variable is the measurable part of the experiment and varies (freely, not manipulated) and thus shows us if it was affected by the manipulation of the independent variable. Depending on the changes of the independent variable, the dependent variable may change (powell, 52).
One example of independent and dependent variables, is that one may believe (or hypothesize) that eating breakfast before school results in good grades. Therefore, since we know the independent variable needs to be manipulated (which would be eating breakfast or not eating breakfast) then, we would relate the grades to whether or not the student ate breakfast. If the student received good grades when eating breakfast before school, we would assume that the statement is true and that the grades (dependent variable) varied on the manipulation of whether or not the student ate breakfast (independent variable).
Here is another breakdown of an example of independent and dependent variables.