Research Designs in Life Span Development Approach

There are two main types of designs are used in all research on human behavior: correlational and experimental.

Correlational Design

In a correlational design, researchers gather information on individuals, generally in natural life circumstances, without altering their experiences. Then they look at relationships between participants’ characteristics and their behavior or development.

Correlation Coefficient (r)—a number that describes how two measures, or variables, are associated with each other.  A correlation coefficient can range in value from +1.00 to −1.00. The magnitude, or size, of the number shows the strength of the relationship. A zero correlation indicates no relationship; the closer the value is to +1.00 or −1.00, the stronger the relationship.

Experimental Design

An experimental design permits inferences about cause and effect because researchers use an evenhanded procedure to assign people to two or more treatment conditions. Through random assignment of participants to treatment conditions, the investigator manipulates an independent variable and examines its effect on a dependent variable. Can be conducted in the laboratory or the natural environment. In an experiment, the events and behaviors of interest are divided into two types: independent and dependent variables.

The independent variable Researcher expects to cause changes in another variable.

The dependent variable – Researcher expects to be influenced by the independent variable.

Quasi-Experimental Design or Modified Experimental design 

  • When researcher cant controlled Independent variable.
  • When Researcher cant assign sample randomly.
  • but researcher will have somehow control to most of the variables playing role in the experiment.
  • For example, experimenters cannot reassign participants to a different gender, ethnicity, age, or educational background.



  • Berk, L. E. (2004). Development through the lifespan. (3rd Ed). New Delhi: Pearson Education Dorling Kindersley India
  • Feldman, R. S., & Babu, N. (2011). Discovering the Life Span. Indian subcontinent adaptation, New Delhi: Dorling Kindersley India


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