Question

What is the difference between an experimental and a correlational study?

Answer 1

• A correlation determines whether there is a relationship between two or more variables. These are co-variables. Therefore, a correlation is used to see whether these co-variables are predictive of each other.
• An experiment is a highly controlled situation, that demonstrates a cause and effect relationship. All relevant variables are held constant, apart from the independent variable (IV). This is the variable being manipulated. The aim is to investigate whether the manipulation of the IV causes the dependent variable (DV) to alter.
• In a correlation study, the researcher or research team does not have control over the variables in the study. The researcher simply measures the data that he/she finds in the world. This allows him/her to see if the two variables are correlated -- whether changes in one are associated with changes in the other. If an increase in one variable tends to be associated with an increase in the other then this is known as a positive correlation. An example would be height and weight. Taller people tend to be heavier.
• In a controlled experiment, the research team has control over the independent variable and other aspects of the experiment. This allows the researchers to make conclusions about whether the independent variable really affects the dependent variable, as opposed to the variables changing at the same time through coincidence. The researcher can also eliminate the effects of other variables. An example is Milgram’s experiment on obedience.