Non-Experimental Methods

Not every research question can be answered with an experiment. Sometimes it is impossible or unethical to manipulate a variable, and sometimes a researcher simply wants to describe or measure relationships as they exist in the world. Non-experimental methods fill this gap. Two of the most important are correlational studies and case studies, each with a distinct logic and set of limitations.

A correlational study measures two or more variables and examines the strength and direction of the relationship between them, without manipulating anything. The relationship is expressed as a correlation coefficient, a number ranging from −1.00 to +1.00. A positive correlation means the variables increase together (for example, hours of study and exam scores), while a negative correlation means one i