How Correlational Studies Are Used in Psychology

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A correlation refers to a relationship between two variables. Correlations can be strong or weak and positive or negative. Sometimes, there is no correlation.

Types of Correlational Research
Illustration by Brianna Gilmartin, Verywell

What Correlation Means

There are three possible outcomes of a correlation study: a positive correlation, a negative correlation, or no correlation. Researchers can present the results using a numerical value called the correlation coefficient.

  • Positive correlations. Both variables increase or decrease at the same time. A correlation coefficient close to +1.00 indicates a strong positive correlation.
  • Negative correlations. As the amount of one variable increases, the other decreases (and vice versa). A correlation coefficient close to -1.00 indicates a strong negative correlation.
  • No correlation. This indicates no relationship between the two variables. A correlation coefficient of 0 indicates no correlation.

Correlation Coefficient

The correlation coefficient is a measure of the correlation strength. It can range from –1.00 (negative) to +1.00 (positive). A correlation coefficient of 0 indicates no correlation.

How Correlational Studies Work

Correlational studies are a type of research often used in psychology, as well as other fields like medicine. Correlational research is a preliminary way to gather information about a topic. The method is also useful if researchers are unable to perform an experiment.

Researchers use correlations to see if a relationship between two or more variables exists, but the variables themselves are not under the control of the researchers.

While correlational research can reveal if there is a relationship between variables, it cannot prove that making changes to one variable will lead to changes to another. In other words, correlational studies cannot prove cause-and-effect relationships.

Types of Correlational Research

There are three types of correlational research: naturalistic observation, the survey method, and archival research. Each type has its own purpose, as well as its pros and cons.

Naturalistic Observation

The naturalistic observation method involves observing and recording the variables of interest in the natural environment without interference or manipulation by the experimenter.

  • Inspire ideas

  • Option if lab experiment not available

  • View variables in natural setting

  • Expensive and time-consuming

  • Extraneous variables can't be controlled

  • No scientific control of variables

  • Participants might behave differently if aware of being observed


  • Can offer ideas for further research
  • Gives the experimenter the opportunity to view the variable of interest in a natural setting
  • Might be the only option if lab experimentation is not possible


  • Can be time-consuming and expensive
  • Does not allow for scientific control of variables
  • Experimenters can't control extraneous variables
  • Subjects may be aware of the observer and may act differently as a result

The Survey Method

Surveys and questionnaires are some of the most common methods that are used for psychological research. The survey method involves having a random sample of participants complete a survey, test, or questionnaire that relates to the variables of interest. Random sampling is vital to the generalizability of a survey's results.

  • Cheap, easy, and fast

  • Flexible

  • Poor survey questions

  • Samples might be unrepresented

  • Outcomes affected by participants


  • Fast, cheap, and easy (researchers can collect large amounts of data in a relatively short amount of time)
  • More flexible than some other methods


  • Can be affected by an unrepresentative sample or poor survey questions
  • Participants can affect the outcome (some participants try to please the researcher, lie to make themselves look better, or have mistaken memories)

Archival Research

Some research benefits from analyzing studies that have been conducted by other researchers or reviewing historical records and case studies.

For example, in an experiment known as "The Irritable Heart," researchers analyzed digitalized records of American Civil War veterans to learn more about post-traumatic stress disorder (PTSD).

  • Large amount of data

  • Less expensive

  • Researchers cannot change participants behavior

  • Can be unreliable

  • Information might be missing

  • No control over data collection methods


  • Can be less expensive than other study methods (researchers can often access data through free archives or records databases)
  • Experimenters cannot introduce changes in participant behavior
  • Large amounts of data provide a better view of trends, relationships, and outcomes


  • Important dates might be missing from the records
  • Previous research might be unreliable
  • Researchers have no control over how data was collected

Limitations of Correlational Studies

You've probably heard the phrase, "correlation does not equal causation." This means that while correlational research can suggest that there is a relationship between two variables, it cannot prove that one variable will change another.

For example, researchers might perform a correlational study that suggests there is a relationship between academic success and a person's self-esteem. However, the study cannot show that academic success changes a person's self-esteem.

To determine why the relationship exists, researchers would need to consider and experiment with other variables, such as the subject's social relationships, cognitive abilities, personality, and socioeconomic status.

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