Variables
Variables are the characteristics, behaviors, changes, etc. that are targeted by a particular scientific study. They can include anything that can be measured, such as weight, age, diet, medical history and so on. The independent variable is the experimental factor that is being manipulated and the variable being studied. The dependent variable is the factor being measured and the variable that may change in response to manipulations of the independent variable. Suppose a researcher wanted to study Vitamin E as a preventive for age spots. The independent variable would be a certain amount of Vitamin E applied daily for the duration of the study and the dependent variable would be age spots. There would also need to be a control condition in which no treatment was undertaken, as a way of seeing if Vitamin E reduced age spots better than doing nothing.