Variables and types

Variables in Experimental Research – Comprehensive Study Material

1. Meaning of Variable

A variable is any characteristic, condition, or factor that can change or vary and can be measured, manipulated, or controlled in a research study.

Examples: age, marks, intelligence, teaching method, motivation, attendance

2. Variables in Experimental Research (Overview)

Experimental research is built on identifying, manipulating, measuring, and controlling variables to establish a cause–effect relationship.

• Independent Variable
• Dependent Variable
• Extraneous Variable
• Control Variable
• Moderator Variable
• Intervening (Mediating) Variable
• Attribute Independent Variable
• Active Independent Variable

3. Independent Variable (IV)

Definition (F. N. Kerlinger):
An independent variable is the presumed cause that is manipulated or selected by the experimenter.

• Deliberately changed by the researcher
• Acts as the cause

🦸 Teaching Method says: “Change me and watch what happens!”

Example: Teaching Method (Activity-based vs Traditional)

Types of Independent Variable

A. Active Independent Variable

• Directly manipulated by the researcher

🦸 Smart Classroom: “Switch me ON or OFF and see the result!”

Example: Use of smart classroom

B. Attribute (Assigned) Independent Variable

• Cannot be manipulated
• Only selected for comparison

👦 Gender says: “You can’t change me—just compare!”

Examples: Gender, locality, school type

4. Dependent Variable (DV)

Definition (Kerlinger):
A dependent variable is the variable on which the effect of the independent variable is observed.

• Outcome or result
• Measured after IV manipulation

📊 Achievement Score says: “I change only if the teaching method changes!”

Example: Students’ achievement score

Types of Dependent Variable

• Primary Dependent Variable: Achievement
• Secondary Dependent Variable: Attitude towards subject

5. Extraneous Variable (EV)

An extraneous variable is any variable other than the independent variable that may influence the dependent variable.

👻 Intelligence, Motivation, Attendance whisper: “We can confuse the result!”

Examples: Intelligence, motivation, prior knowledge, home environment

Types of Extraneous Variables

• Subject-related: intelligence, anxiety
• Situational: noise, lighting, time of day
• Procedural: teacher bias, test difficulty

6. Control Variable (CV)

A control variable is an extraneous variable that is kept constant throughout the experiment.

🛑 Teacher: “Same teacher, same syllabus, same test!”

Examples: Same teacher, syllabus, duration, evaluation method

7. Moderator Variable

A moderator variable affects the strength or direction of the relationship between IV and DV.

🎚️ Motivation turns the volume: “The method works stronger for some students!”

Example: Teaching Method × Motivation → Achievement

8. Intervening (Mediating) Variable

An intervening variable explains how or why the independent variable affects the dependent variable.

🌉 Student Engagement says: “First me, then marks!”

Example: Teaching Method → Engagement → Achievement

9. Complete Classroom Example

Variable Type	Example
Independent	Activity-based teaching
Dependent	Achievement score
Extraneous	Intelligence, motivation
Control	Same teacher, syllabus
Moderator	Motivation
Intervening	Engagement

10. One-Line Exam Definitions

• Variable: A measurable characteristic that can change.
• Independent Variable: Presumed cause manipulated by researcher.
• Dependent Variable: Presumed effect measured in a study.
• Extraneous Variable: Unwanted variable influencing results.
• Control Variable: Extraneous variable kept constant.
• Moderator Variable: Changes strength of IV–DV relationship.
• Intervening Variable: Explains how IV affects DV.

Change ONE (IV) → Measure ONE (DV) → Control MANY (EV) → Explain HOW (Intervening) → Check WHEN/WHO (Moderator)

11. Conclusion

Variables form the foundation of experimental research. Valid experimentation requires manipulation of the independent variable, measurement of the dependent variable, and control of extraneous variables to establish a true cause–effect relationship.