Variables: Independent, Dependent and Controlled
Background: When conducting
experiments, one needs to deal with variables,
those factors or elements that are likely to vary or change. A typical study
has an independent variable and a dependent variable.
The independent (or manipulated) variable
is something that the experimenter purposely changes or varies over the course
of the investigation. The dependent (or responding) variable is the one that
is observed and likely changes in response to the independent variable.
For example, a student might
change the position of a plane’s wing to see how it affects the average
speed of a model plane. The wing position would be the independent variable-
because the student purposely changes its location. The average speed would be
the dependent variable since the average speed would depend on the location of
the wing.
Independent Variable =
Wing Position
Dependent Variable = Average
Speed
When conducting an experiment,
all other variables must be kept the same throughout the investigation; they
should be controlled. The variables
that are not changed are called controlled variables.