When conducting an experiment, a researcher needs to define the study groups. There must be<em> at least one </em><em>experimental </em><em>group</em>. <em>The </em><em>control </em><em>group may be useful but not critical</em>.
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When conducting an experiment, there are different aspects to consider, such as the question that drives to the reseach, the hypothesis, theoretical framework, variables involved -independent, dependent, and control-, methodology, study groups, data analisys, among others.
During an experiment, the researcher applies different treatments to the <u>experimental groups</u> to analyze their response. It is also useful to have a control group to observe how it responds when no treatment is applied. In these situations, the researcher compares at least two groups: a control group and an experimental group. Both groups are composed of individuals coming from the same population, so they are identical in all aspects except for the independent variables.
• The control group is used to <em>identify any other factors influencing the results</em> obtained in the study, apart from the modified variables of the treatment. The independent variable keeps constant in the control group.
• The experimental group receives the treatment. The researcher voluntarily <em>changes the values of the independent variable </em>to observe how it affects the individuals subjected. There can be<em> several experimental groups. </em>
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