Which one of the following types of variables is most difficult to evaluate objectively in a true experiment?

Which one of the following types of variables is most difficult to evaluate objectively in a true experiment? Explain why you think that (See instructions below).

a)      Dependent variable
b)     Independent variable
c)      Confounding variable
d)     Extraneous variable
e)      None of the above

Instructions: Make selection, provide a concept definition (text), and support your opinion on the selection with an example from research that illustrates the concept. Do so in a maximum of 250 words.  Use credible and peer reviewed sources. Credible sources include course materials, University Library research that is peer reviewed, and Internet sites ending in .edu or .gov with with the one exception of research pulled from the www.apa.org site. If research is pulled from the APA site, use the www.apa.org


1.The variable that is the most difficult to evaluate objectively in a true experiment would be Extraneous variable. According to Cozby & Bates (2015), “It would be impossible to know whether participants that were participating in an aerobics class or those watching aerobics on video, would have a better mood due to what they were doing” (p.162). With extraneous variable there are so many other factors that come into play such as; does either room have more doors, air conditioning, heating, windows, ect. Those things actually can change the response of each group making the data collected unreliable. In an article I found regarding women who are pregnant and using cocaine, the study that was done took place over quite a few years. According to Richardson & Day (1999), “One of the issues that were identified was the failure to control adequately for extraneous variables” (p.234). The researchers realized that some of the studies were inadequate and that most of the time information was not interpreted correctly to the client or their providers. The lack of communication caused further issues and endangered some of those pregnancies. Since the study on prenatal cocaine exposure was performed over such a lengthy period of time it is hard to make sure that there will not be anything extraneous that would have an effect on the study. Without trying to eliminate those extraneous variables the study becomes compromised and the data does not appear to be as relevant as other studies.


Cozby, P. C., & Bates, S. C. (2015). Methods in Behavioral Research (12th ed.). New York, NY: McGraw-Hill.

Richardson, G. A., & Day, N. L. (1999). Studies of prenatal cocaine exposure: Assessing the influence of extraneous variables. Journal of Drug Issues, 29(2), 225-236. Retrieved from https://search-proquest-com.contentproxy.phoenix.edu/docview/208833439?accountid=458

2.Independent variables are tested to see of the have an effect on the dependent variable, which is why the extraneous variables (not intentionally studied) are known to be undesirable variables, and sometimes they are difficult for the researcher to control (Cozby, 2015). As an example, since the extraneous variable is not a variable of interest, they may still influence an outcome of a research study or experiment.  According to Losen & Oyinalde (2014), the extraneous variable has its positives as it can be used to provide alternative explanations when coming to the experiments effects, but it must be controlled for and not take the place of the independent variable, which has to determine the actual effects. References:Cozby, P. C., & Bates, S. C. (2015). Methods in Behavioral Research (12th ed.). New York, NY: McGraw-Hill. Losen, A., & Oyinalde, A.O (2014) Extraneous Effects of Race, Gender, and Race-Gender Homo- and Heterophily Conditions on Data Quality   4(1)   Directory of Open Access Journals DOI: 10.1177/2158244014525418

3.The variable that I think is most difficult to evaluate is the confounding variable. In our reading from chapter four they talk in depth about the confounding variable. They explain the third variable that is hard to get a read on. According to Cozby & Bates (2015) the confounding variable is what we call the third when an uncontrolled one is operating. When a third variable is operating it can cause a huge problem since it can introduce an alternative explanation which can reduce the overall validity of the study (Cozby & Bates, 2015). If two variables are confounded they are so intertwined that you will not be able to determine which of the variables is operating in a situation (Cozby & Bates, 2015). The example they give is about how exercise can cause a reduction in anxiety but when they input income that can cause the third variable (Cozby & Bates, 2015). The third variable which can be extraneous to the two variables being studied. There can be any number of third variables that may be responsible a relationship between two variables (Cozby & Bates, 2015).

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