Extraneous variables are the variables that explain the outcome of an experiment which are sometimes seen as the interest, it can also be explained as the undesirable variables that influence the relationship between the variables that an experimenter is examining. Extraneous variables are not independent and because of that they can always affect the dependent variables. The dependent variable does not change but it can be measured. extraneous variables affect dependent variables through confounding variables which is seen through an example where a researcher gives out an assignments to the targeted group through a new strategy that he or she wants to find out how the strategy works ,then some per knowledge is found by the targeted group which will affect their ways of doing the assignment that the researcher tested earlier and trough this their results are seen to be affected. All these happens because of confounding variables which affect the dependent variable. a confounding variable it must influence the dependent variable. If the extraneous variable is totally unrelated to the dependent variable then it is not a threat.

Dependent variable can also be affected by the situational variable which affect the participants through noise which is found to be so much in the environment and also the increasing temperature that will always affect the participants

Researchers have attempted to control the extraneous variable in five ways that is through

Homogeneous sample –this is one simple and effective way of controlling an extraneous variable is not to be allowed to vary. This homogeneous sample works when the researcher sees that one of the research strategy is not going to work out for example if the research work involves both genders and the researcher realizes one gender can affect the research ,he the n decides to work work with only one gender which is suitable for the research.

Matching –this is when randomization is not possible, or when the experimental groups are too small and contain some crucial variables, subjects can be matched for those variables. $he experimenter chooses subject’s match each other for the special variable. This control is always seen to be difficult and cumbersome since it involves so much grouping work that is also time consuming.

Randomization-this is the best way to control he extraneous variable because the researcher finds that the groups used for research are totally equal. The probability that the groups are not equal is less has the probability that the groups are equal ,therefore the distribution of the materials is done equally to the all groups and this makes research more easy and faster

Statistical control- this is where the statics are just removed or subtracted from the variables

Building the extraneous variable from the design-this is building the variables into independent variable in which afterwords the results of the effect can be measured.

References

Morabia, A. (2011). History of the modern epidemiological concept of confounding. Journal of epidemiology and community health, 65(4), 297-300.

Emanuel, Ezekiel J; Miller, Franklin G (Sep 20, 2001). “The Ethics of Placebo-Controlled Trials—A Middle Ground”. New England Journal of Medicine. 345 (12):