How is a controlled experiment performed

In experiments scientists compare a control group and an experimental group that are identical in all respects, except for one difference - experimental manipulation. Unlike the experimental group, the control group is not exposed to the independent variable under investigation and so provides a base line against which any changes in the experimental group can be compared.

Since experimental manipulation is the only difference between the experimental and control groups, we can be sure that any differences between the two are due to experimental manipulation rather than chance. Randomly allocating participants to independent variable groups means that all participants should have an equal chance of taking part in each condition. The principle of random allocation is to avoid bias in the way the experiment is carried out and to limit the effects of participant variables.

The researcher wants to make sure that it is the manipulation of the independent variable that has changed the changes in the dependent variable. Hence, all the other variables that could affect the dependent variable to change must be controlled. These other variables are called extraneous or confounding variables.

Extraneous variables should be controlled were possible, as they might be important enough to provide alternative explanations for the effects. For example, it would be difficult to control variables that have happened in the past.

A researcher can only control the current environment of participants, such as time of day and noise levels. Scientists use controlled experiments because they allow for precise control of extraneous and independent variables. This allows a cause and effect relationship to be established.

Although it is harder to draw conclusions from uncontrolled experiments, new patterns often emerge that would not have been observable in a controlled experiment. For example, you may notice the diet drug seems to work for female subjects, but not for male subjects, and this may lead to further experimentation and a possible breakthrough.

If you had only been able to perform a controlled experiment, perhaps on male clones alone, you would have missed this connection. Actively scan device characteristics for identification.

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Click the Test button to start the experiment. Repeat the experiment and test a different jacket material or color. Analyze your data: Analyze the data in the Table.

Click the Graph button to see your results graphed. Explain any patterns you observed. Do NOT type your answers here. Draw a conclusion about how color affects heat absorption Do NOT type your answers here. Why or why not? How does the material of the jacket affect heat absorption? Describe the strengths and weaknesses of the computer model you used in the experiment. What other parameters could you use in such an experiment to determine the effect of color on heatabsorption? No tags were found Short-link Link Embed.

Share from cover. Share from page:. Page 2: 3. That makes it harder to apply your findings outside of a controlled setting. Controlled experiments require:. Depending on your study topic, there are various other methods of controlling variables.

An experimental group, also known as a treatment group, receives the treatment whose effect researchers wish to study, whereas a control group does not. They should be identical in all other ways. Experimental design means planning a set of procedures to investigate a relationship between variables.

To design a controlled experiment, you need:. Experimental design is essential to the internal and external validity of your experiment. Have a language expert improve your writing. Check your paper for plagiarism in 10 minutes. Do the check. Generate your APA citations for free! APA Citation Generator. Home Knowledge Base Methodology What is a controlled experiment?

What is a controlled experiment? Controlling variables can involve: holding variables at a constant or restricted level e.