Anonymous asks:

What are control groups and test groups?

i have a science fair project on growing mold on cheese and it asks what is the control groups and test groups. i have no idea what it means by that because my teacher doesn't explain anything.
In Topics: Science fair
> 60 days ago



Feb 4, 2014
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What the Expert Says:

I hope you have found your answer by another means by now. We get so many questions that it is really hard to keep up and sometimes questions like yours get behind in the stack for one reason or another. I'm sorry! Anyway, as I hope you have found out, some experiments divide subjects into two groups, the experimental group and the control group. The difference is that the experimental group is exposed to something related to the experiment, say, a chemical, and the control group is not exposed to it. In other words, some procedure is performed on the experimental group – it is the group exposed to the independent (manipulated) variable being tested. The one in which the changes will be observed and recorded.

A control group, which should be just like the experimental one in every way except for the chemical, for example, is kept separate from the rest of the experiment so it won’t affect the results. This isolates the independent variable's effects on the experiment and can help rule out other explanations of what happens.

Not all experiments need a control group, but they are useful where the experimental conditions are complicated and multiple variables are involved, like in a CSI, or medical diagnosis investigation. Experiments that use control groups are called controlled experiments.

Always, the independent variable is what is manipulated, what you change. The dependent variable is the responding one, what changes as a result of what you do. Hope this helps review at least! Best wishes.

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