Transcript Independent and Dependent Variables

Independent and Dependent
Variables
Definition
• In an experiment, the independent variable is
the variable that is varied or manipulated by
the researcher, and the dependent variable is
the response that is measured.
Example Number 1
• Independent Variable: A scientist studies the
impact of a drug on cancer. The independent
variable is the administration of the drug.
• Dependent variable is the impact the drug has on
cancer.
• You can vary the independent variable and see
what happens to the dependent variable. For
instance, you could vary the dose and see how
the increased or decreased dose affects the
cancer.
Example 2
• A scientist studies how many days people can
eat soup until they get sick. The independent
variable is the number of days of consuming
soup.
• The dependent variable is the onset of illness.
Example 3
• If you conduct an experiment on the effect of
talking on plant growth, the number of
minutes you talk to the plant is the
independent variable.
• The dependent variable is the amount that
the plant grows.
Example 4
• The effect of temperature on E. coli bacterial
growth.
• Independent variable (varied by the
researcher) is temperature.
• Dependent variable is the rate of the growth
of E. coli bacteria.
Example 5
• The effects of touch (pressure) on the firing of
neurons in Aplysia californica.
• Independent variable is the intensity of the
“touch.”
• The dependent variable is the intensity of
neurons firing.