Correlation vs. CausationTutorial

Ed 8113 Summer 2004Cynthia Joffrion

In this Tutorial you will learn:

• To distinguish the difference between the concepts of correlation and causation.

• Attributes of Correlation and Causal research.

Definitions

• The Concise Oxford Dictionary defines correlation as “mutual relation between two or more things” and causation as “causing or producing an effect”.

• If two variables are highly correlated it does not necessarily mean that one causes the other. To simply say that a correlation exists does not imply causation.

Correlation is different from causation…• Correlation is when two or more things or

events tend to occur at about the same time and might be associated with each other, but aren't necessarily connected by a cause/effect relationship. For example, sick people tend to have a runny nose and a sore throat. These two variables correlate to each other in that they tend to show up in the same patients. That doesn't mean runny noses cause sore throats, or that sore throats cause runny noses

Confusion between Correlation and Causation.

• There are many examples of correlation that are incorrectly interpreted as causation.• Bathing suit color and the number of shark attacks

on swimmers are corrlated.• The number of siblings in elementary school

children and vocabluary size have a strong positive correlation

Quick Quiz

• Click on the example of a correlation that is not incorrectly interpreted as causation.

• Skirt lengths and stock prices are both controlled by the general attitude of the county.

• The number of cavities and children’s vocabulary are both related to a child’s age.

• Children raised by single parents do less well at school.• None of the above

Correlation Research Attributes• What is correlation Research?

• In correlation research, researchers investigate possible relationships among variables without trying to influence those variables. Although correlation studies cannot determine the causes of relationships, they can suggest them.

• What is the purpose of Correlation Research?• Correlation research is carried out for one of two

basic purposes-either to help explain important human behaviors or to predict likely outcomes.

Causal-Comparative Research Attributes

• What is Causal-Comparative research?• In Causal-Comparative research allows researchers to

investigate the possibility of a causal relationship among variables that cannot, as in experimental research, be manipulated. Two groups that are different on a particular variable are compared on another variable.

• What is the purpose of Causal-Comparative research?• In Causal-Comparative research, investigators attempt

to determine the cause or consequences of differences that already exist between or among groups of individuals.

Similarities Between Causal-Comparative and Correlation Research.

• Both causal-comparative and correlation studies are examples of associational research. Researchers who conduct both studies seek to explore relationships among variables.

• Both seek to identify variables that are worthy of later exploration through experimental research, and both often provide guidance for subsequent experimental studies.

Differences Between Causal-Comparative and Correlation Research.

• Causal-comparative studies typically compare two or more groups of subjects, while correlational studies require a score on each variable for each subject.

• Correlational studies investigate two (or more) quantitative variables, whereas causal-comparative studies involve at least one categorical variable.

• Correlational studies analyze data using scatter plots and/or correlation coefficients, while causal-comparative studies compare averages or use cross break tables.

Differences Between Causal-Comparative and Correlation Research.

• In experimental research, the independent variable is manipulated; in causal comparative research, no manipulation takes places

Quick Quiz

• Please select the statement that is false• Both causal-comparative and correlation studies are

examples of associational research• Causal-comparative studies typically compare two

or more groups of subjects, while correlational studies require a score on each variable for each subject

• In experimental research, the independent variable is not manipulated; in causal comparative research, manipulation takes places

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References

Fraenkel, J.R. & Wallen, N. E. (1996). How to design and evaluate research in education. Mcgraw-Hill, Inc.

Gall, M.D., Gall, J.P. & Walter, R, B. (2003). Educational research: An introduction. Pearson Education, Inc.

Kerlinger, F. N. (1979). Behavioral research: A conceptual approach.

National Center of Education Statistics. (2003). Handbook of survey methods: Technical Report. Retrieved from http://www.nces.ed.govPicciano, A. (2004). Edstats primer. Retrieved July 20, 2003 from http://www.hunter.cuny.edu/edu/apiccian/edstat06.html