Research Methods and Research Designs

Lifespan Development

Dr. Ye Wang | TR 2:30 | September 17, 2026

Research Methods

  • Research methods are ways researchers learn about different subjects and gather information.

Issues in Lifespan Development

Researchers study different questions about how people develop:

  • Nature vs. Nurture – Is development influenced more by genetics or the environment?

  • Continuity vs. Discontinuity – Does development happen gradually or in stages?

  • Active vs. Passive – Do people actively influence their own development, or are they mainly influenced by their environment?

  • Stability vs. Change – What stays the same, and what changes as people develop?

Research Designs

1. Descriptive Research

  • Describes what is happening at a certain time.

  • Does not explain why something happens.

2. Correlational Research

  • Looks for relationships between variables.

  • Can help researchers predict future events.

  • Correlation does NOT prove cause and effect.

3. Experimental Research

  • Researchers change or manipulate one or more variables.

  • They look at how the change affects something else.

  • Helps researchers study cause and effect.

Third Variable

  • A third variable is something outside the main study that may affect the relationship between two variables.

  • It can make two things appear related even when one does not actually cause the other.

Example:
Ice cream sales and swimming accidents may both increase in the summer. The hot weather is a third variable that affects both.

⭐ Important to Remember

  • Descriptive = What is happening?

  • Correlational = What is related?

  • Experimental = What causes what?

  • Correlation does not prove causation.

  • A third variable can affect the results of a study.