research methods

Research Methods

Research Method

Definition

Advantages

Disadvantages

Naturalistic Observation

Observing behavior in its normal environment without interference.

• Real-life behavior
• High ecological validity
• Useful for studying behaviors that cannot be manipulated

• Little control over variables
• Cannot determine cause and effect
• Observer bias may occur

Case Study

An in-depth investigation of one individual or a small group.

• Provides detailed information
• Useful for studying rare conditions
• Can generate new research ideas

• Cannot be generalized to everyone
• Time-consuming
• Researcher bias is possible

Survey

Collecting information by asking participants questions through interviews or questionnaires.

• Can collect data from many people quickly
• Cost-effective
• Useful for attitudes and opinions

• Responses may be inaccurate or dishonest
• Participants may misunderstand questions
• Cannot establish cause and effect

Correlational Research

Examines the relationship between two or more variables without manipulating them.

• Identifies relationships
• Useful when experiments are not ethical or practical

• Correlation does not equal causation
• Cannot determine which variable caused the relationship

Experiment

Researchers manipulate an independent variable to determine its effect on a dependent variable.

• Only research method that can determine cause and effect
• High level of control over variables

• May occur in artificial settings
• Some variables cannot be ethically manipulated

Time-Span Research Designs

Developmental psychologists often want to know how people change over time. Chapter 1 discusses three major designs.

1. Cross-Sectional Design

Definition

Researchers compare different age groups at one point in time.

Example

A researcher compares:

  • 5-year-olds

  • 10-year-olds

  • 15-year-olds

All during the same year.

Advantages

  • Quick

  • Less expensive

  • No participant dropout

  • Easy to conduct

Disadvantages

  • Does not show individual development over time

  • Cohort effects (people born in different generations may differ because of historical experiences)

Best For

Comparing age differences.

2. Longitudinal Design

Definition

Researchers study the same individuals over an extended period.

Example

Following the same children from birth until age 18.

Advantages

  • Shows actual developmental change

  • Tracks individual growth

  • Eliminates cohort differences

Disadvantages

  • Expensive

  • Time-consuming

  • Participants may drop out (attrition)

  • Results may become outdated

Best For

Studying developmental change over time.

3. Sequential Design (Cross-Sequential)

Definition

Combines cross-sectional and longitudinal research.

Researchers study multiple age groups over time.

Example

A researcher follows groups of:

  • 5-year-olds

  • 10-year-olds

  • 15-year-olds

for several years.

Advantages

  • Reduces cohort effects

  • Provides more complete developmental information

  • Combines strengths of both methods

Disadvantages

  • Most expensive

  • Most time-consuming

  • Complex to conduct and analyze

Best For

Obtaining the most comprehensive picture of development.

Reliability and Validity

These concepts help determine the quality of research.

Reliability

Definition

The consistency of a research measure.

Example

A developmental test should produce similar results each time it is administered under similar conditions.

Easy Way to Remember

Reliable = Repeatable

Validity

Definition

The extent to which a study measures what it is intended to measure.

Example

An intelligence test should accurately measure intelligence—not reading ability or test-taking skills.

Easy Way to Remember

Valid = Accurate

Ethical Guidelines in Developmental Research

Researchers must protect participants by following ethical standards.

Informed Consent

Participants (or parents/guardians for children) must understand the study and agree to participate voluntarily.

Confidentiality

Researchers must protect participants' personal information.

Protection from Harm

Participants should not experience unnecessary physical or psychological harm.

Right to Withdraw

Participants can leave the study at any time without penalty.

Institutional Review Board (IRB)

A committee that reviews research proposals to ensure ethical standards are met.

Quick Comparison Table

Method

Cause & Effect?

Strength

Weakness

Naturalistic Observation

❌ No

Real-world behavior

Little control

Case Study

❌ No

Detailed information

Not generalizable

Survey

❌ No

Large samples quickly

Self-report bias

Correlational

❌ No

Finds relationships

Cannot prove causation

Experimental

✅ Yes

Determines cause and effect

May be artificial

Time-Span Design Comparison

Design

Participants

Time

Major Advantage

Major Disadvantage

Cross-Sectional

Different age groups

One point in time

Fast and inexpensive

Cohort effects

Longitudinal

Same participants

Many years

Tracks developmental change

Attrition, time, cost

Sequential

Multiple age groups followed over time

Several years

Reduces cohort effects

Most expensive and complex

High-Yield Exam Points

Be prepared to answer these common questions:

  • Which research method can establish cause and effect?

    • Experimental research

  • What is the biggest limitation of correlational research?

    • Correlation does not prove causation.

  • Which research design is the fastest?

    • Cross-sectional design

  • Which design studies the same people over many years?

    • Longitudinal design

  • Which design combines cross-sectional and longitudinal methods?

    • Sequential design

  • What is the main advantage of a case study?

    • Provides detailed information about an individual or small group.

  • What is the difference between reliability and validity?

    • Reliability = consistency; Validity = accuracy.