IV, DV & EV

IV and DV

• The independent variable (IV) is the variable that is systematically manipulated or varied in some way by the experimenter
• The dependent variable (DV) is the aspect of the participant’s behaviour that is observed or measured

Identify the IV and DV

• That smoking while driving increases driver alertness
• That alcohol impairs performance on a memory task.
• That too much stress causes stomach ulcers.
• That drinking red cordial increases hyperactivity in children.
• That brain wave activity changes during sleep

Extraneous Variable (EV)

• Any variable other than the IV that could potentially cause changes in the DV and therefore affect the results in an unwanted way

Does sleep deprivation cause headaches?
IV – sleep deprivation
DV- number of headaches
What other variables other than the IV may affect DV? (EV)
foods eaten
sleeping pills
level of stress in participants’ lives
activity before sleep
Amount of alcohol consumed before sleep
Medications?

Untitled Slide

• The effect of the Milkshake diet on weight reduction. IV = DV = Extraneous variables =