Independent vs. Dependent Variables: Clear Definition & Examples

Core Definitions

• Independent Variable (IV): The factor the researcher manipulates (the “cause”).
• Dependent Variable (DV): The outcome measured (the “effect”).

Classic Examples

Experiment	IV	DV
Caffeine → alertness	Caffeine dose (0, 100, 200 mg)	Reaction time / EEG alertness
Fertilizer → plant growth	Fertilizer amount	Plant height
Sleep deprivation → memory	Hours of sleep loss	Memory test score
Music → mood	Music genre	Mood rating
Self‑controlled: exercise → weight	Exercise regimen	Weight change (same variable measured pre/post)

Complexities

• Multiple IVs or DVs possible.
• Relationships may be non‑linear or mediated.
• Confounding variables must be controlled.

Careful IV/DV definition enables causal inference.