Question

Can you think of a problem in your own nursing practice with multiple extraneous variables? How would you control these multiple extraneous variables in a research study?

Answer 1

Extraneous Variables are undesirable variables that influence the relationship between the variables that an experimenter is examining. Simply put extraneous variables are those which are not 'considered for' during an experiment but influence the outcome of the experiment. When an experiment is performed, the expected outcome is to understand the relational or causal relationships between the main variables, however extraneous variable may adversely affect this outcome. Having multiple extraneous variables to account for is an extremely challenging process in any research.

For a medical experiment where the affect of an ACE inhibitor is to be considered on blood pressure many other extraneous variables come into play. These variables include age, normal systolic blood pressure, herediatry history, diet, etc. Controlling the effect of such variables is very tedious and important part of an experiment. Many techiniques can be employed in order to control these variables.

Randomization - We can make sure that groups are selected at random and medication is also assigned randomly which could decrease bias within the group.

Matching or Uniformity - If two or more groups which are in the experiment have the same confounding variables like gender, age, income etc.which could then be distributed equally amongst the group.

Experimental Control - The challenge is to develop a research design that will eliminate or reduce sources of systematic error and random error and is also internally valid.

Statistical Control - Another method that may work to bring down the effect of extraneous variables is the method of statistical control. Among the various statistical tools and techniques, Analysis of Variance ( ANOVA) helps in reducing the impact of the extraneous factors on the study.