A Controlled Experiment

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A controlled experiment tests only one variable and all other factors remain the same.

Variable: A factor that can change. A variable can change other factors when it changes.

Examples of variables:

-Temperature

-Light

- Open vs. Closed container

-Location

-Time

-Elevation

The independent variable is the variable that is purposely changed. It is the manipulated variable.

The dependent variable changes in response to the independent variable. It is the responding variable.

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The dependent variable is a factor that changes because the independent variable changes. However the independent variable is not changed by the dependent variable.

Example: Elevation and Boiling temperature of water. The boiling temperature of water changes because of changes in elevation. Changes in the boiling temperature of water do not change elevation.

In a Controlled experiment only one variable is allowed to change at a time. Everything else remains constant.

Experimental Error

Bias (what you expect to happen prevents you from observing what actually happens)

Testing more than one independent variable.

Not having a control group.

Not having constants.

Not using a large enough test group.

Not repeating the experiment enough times.

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Replicates

In an experiment multiple copies of the experiment are done at the same time.

This is to ensure that the results are accurate (true) and not due to a mistake, error or chance event.

Treatments

Set of variables in the experiment that are the same in each group of replicates.

What is a controlled experiment?

An experiment with one group of test subjects being exposed to the variable, and one that is not exposed to the variable

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Controlled Experiment

What are the groups in a controlled experiment?

Control Group

-Gets NORMAL treatment (No Variable).

-Used for comparison

Experimental Group

Gets the VARIABLE you are testing.

In the pinto bean experiment, which is the control group and which is the experimental group?

Control Group: Experimental Group:

Fresh water beans Salt Water Beans