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Extraneous variables may have an influence on the dependent variable. In what ways do researchers attempt to control extraneous variables? Support your answer with current literature.

Extraneous variables are the undesirable variables that are present in every experiment and influence the outcome of an experiment. Extraneous variables are variables are not the independent variables but have an effect on the results of an experiment. Extraneous variables are not of interest to the experiment. Extraneous variables usually add error to an experiment and as a result, the researcher aims to control the extraneous variables in the research study. There are different types of extraneous variables such as situational variables that include; lighting and noise and experimenter effect variables (Pourhoseingholi et al., 2012).

One of the ways that researchers can decrease the amount of extraneous variables is through random sampling. Random sampling is the process where a researcher selects a study sample from a larger population by assigning equal probability to every member of the population. Although random sampling does not eliminate the extraneous variables it ensures that the effect is spread across the entire study population (Pourhoseingholi, et al., 2012). Therefore, the use of random sampling decreases the effect of systematic error, the type of error that varies with the independent variables. Another way that a researcher may use to control extraneous variables is by identifying the variables that are most likely to influence the dependent variable. A research identifies the variables by past experience on controlling extraneous variables and through logical reasoning (Krauth, 2000). For instance, if a researcher is measuring memory, variables that may affect the outcome include noise and other distractions. Additionally, a researcher can control extraneous variables by holding it constant. A researcher can do this by standardizing the environment of the study (Krauth, 2000). For instance, a researcher can take the research study in the same time, day and by the same researcher. Therefore holding the variables constant eliminates the possibility of the extraneous variables confounding.

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