What are extraneous variables?

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In this blog we will discuss what extraneous variables are.

We will also discuss what are the different types of extraneous variables and how one can control these variables. 

What are extraneous variables?

Extraneous variable is anything that is not being intentionally studied yet has the potential to affect the results of the study or has an effect on the dependent variable which in turn can impact the outcome of the study.

Another way to understand what extraneous variables is understanding that it refers to any other variable- that is not an independent variable- but has the ability to influence or impact the results of the study

For example, Extraneous variables within a human population in research can include intelligence levels, gender, or age. When it comes to situational extraneous variables it could include lighting or noise in the setting that impacts results. 

More elaborately, let us take an example of how online learning can impact the understanding of a subject in students where one group uses online learning and the control group uses traditional learning methods. 

In this case, an extraneous variable can include support at home that they receive outside of school learning or it could also include the students intelligence or their prior knowledge of the subject- all of this can influence test scores which might lead to inconclusive results for the study since it does not give a clear picture of whether the differences in scores is due to the learning method or due to other variables. 

What are the types of extraneous variables?

Here are the different types of extraneous variables:

Situational Variables

This kind of extraneous variable refers to the aspects of the environment and the situation where the testing or the study is being conducted that has the potential to affect the subject or the participant of the study. 

These can include the temperature of the room, the lighting, the noise present as well as the presence of other individuals in the room, the manner in which testing instructions are given out etc. 

It becomes important that the researcher makes an attempt to make the testing conditions exactly the same for each and every participant so that the environment and the procedures are standardised for each subject. 

Participant / Person Variable

This extraneous variable refers to the differences in each individual participant which has an effect on the results of the study. This can include factors like mood, intelligence, anxiety, nerves, concentration etc.

For example, one of the participants for an IQ test had not gotten enough sleep the night before due to which they were tired. This could have influenced their performance and their results. This would be considered a person variable 

Participant variables can be controlled if the experimenter uses a random method of allocating conditions of the independent variable. 

Experimenter / Investigator Effects

Another extraneous variety that can have an impact on the results of the study include the  experimenter’s impact on the participants’ behaviours.

This particular influence and effect is often unconsciously conveyed by giving unintentional cues of how the participant should behave. This is called experimenter bias and the experiment is often totally unaware of their influence as they review the results. 

Other effects of this particular extraneous variable include the personal attributes of the experiementor for example: gender, race, age, manner, dressing, accent etc. 

Demand characteristics

Demand characteristics are another form of extraneous variables that include all the subtle cues that convey to the subjects of the study about the purpose of the research without being told directly. 

This will include all the other variables mentioned above as well as the interpretation of the participants about what is going on in the situation.

One way the experimenters can attempt to minimise these factors is by keeping the environment as natural as possible and following standardised procedures for testing.

What are confounding extraneous variables?

A confounding extraneous variable is a type of extraneous variable that directly impacts or interferes with the outcome of a study by affecting both the dependent and independent variables, as well as the outcome of the study.

This particular type of extraneous variable often misleads researchers to believe that there is a cause and effect relationship between two variables when there is not. 

For example, in a research that involves understanding the effect of lack of exercise on weight gain,  lack of exercise is the independent variable and weight gain is the dependent variable.

The researchers might  conclude that the lack of exercise leads to weight gain however, one confounding variable could include how much the participants eat in a day or their metabolism rate, as well as their age- all of which might influence their weight gain versus their level of exercise.

The researchers might conclude that the lack of exercise is leading to weight gain however it could simply be that the participants were eating more during that period of time.

How to control extraneous variables?

Any researcher who wants to gather clear results of their study, they will want to make sure that any manipulation of the independent variable is what causes the impact on the dependent variable and no other variable. 

This is why it becomes so important that these extraneous variables are controlled so that it has no impact on the dependent variable. 

Here are a few ways you can control the extraneous variables:

Determine which type of extraneous variables are present in your study

The first thing you can do is to identify any possible extranoys variables that are present in your study. 

For example, if you are conducting an interview or a survey, cross checking your list of items to check whether they contain cues about the purpose of the study or not. 

Another thing you can do is to cross check any envilemtal factors that can impact results such as lack of proper lighting, temperature issues in the testing area etc.

Select a method of control

Next, you can select a method of control to tackle the impact of the extraneous variables on your participants. Some of the methods that you can use include:

  • Random sampling can be one method that can help the sample be representative of the population that is being studied by giving participants an equal chance of being chosen for the study by giving the same odds to each participant of being part of the study group.
  • Another method is to Standardise the procedures when designing the study to keep the environment the same for each participant. One way the experimenters can attempt to minimise these factors is by keeping the environment as natural as possible and following standardised procedures for testing
  • Counterbalancing where different participants are tested in different orders for example, some participants complete “step one” first while another group completes “step two” first- this is done to control nuisance variables
  • Masking, also known as the double-blind method, where the experiment is administered to the participants by someone who also is not aware of the purpose of the test. This is done to remove or reduce experimenter bias.

Implement the method of control

The next thing you can do after strategically identify what method of control you would like to implement is to implement them into the study and the process of the experiment. 

Consistent environment.

It becomes important that the researcher makes an attempt to make the testing conditions exactly the same for each and every participant so that the environment and the procedures are standardised for each subject. 

One way the experimenters can attempt to minimise these factors is by keeping the environment as natural as possible and following standardised procedures for testing.

What are variables?

A variable in research simply refers to the subject or object such as a person, place, thing, or phenomenon that you are trying to measure. 

A research variable also refers to any variable that has some kind of cause and effect relationship and is something that we are trying to measure, manipulate, study, and control. 

Variables in research other than extraneous variables include:

  • Dependent Variable which is dependent on other factors that are being measured, these variables are expected to change as a result of manipulation. 
  • Independent Variable which is stable and unaffected by the other variables you are trying to measure. It is the variable that is systematically manipulated and is presumed the cause. 
  • Control variables are those variables that are held constant throughout the experiment.
  • Confounding variables is one that hides the true effect of another variable in your experiment. Usually happens when a closely related variable is present to the variable that is desired and studied. 
  • Latent variables is one that can’t be directly measured, but that you represent via a proxy.
  • Composite variables which is a combination of multiple variables in an experiment often created during the analysis of data and not measurement. 

Conclusion

In this blog we have discussed what extraneous variables are.

We have also discussed what are the different types of extraneous variables and how one can control these variables. 

What are the 4 types of extraneous variables?

Here are the different types of extraneous variables:

  • Situational Variables: This kind of extraneous variable refers to the aspects of the environment and the situation where the testing or the study is being conducted.
  • Participant / Person Variable which refers to the differences in each individual participant which has an effect on the results of the study.
  • Experimenter / Investigator Effects which include the  experimenter’s impact on the participants’ behaviours.
  • Demand characteristics are another form of extraneous variables that include all the subtle cues that convey to the subjects of the study about the purpose of the research without being told directly. 

How can extraneous variables be controlled?

Any researcher who wants to gather clear results of their study, they will want to make sure that any manipulation of the independent variable is what causes the impact on the dependent variable and no other variable. 

This is why it becomes so important that these extraneous variables are controlled so that it has no impact on the dependent variable. 

Here are a few ways you can control the extraneous variables:

  • Random sampling
  • Masking
  • Standardise the procedures
  • Counterbalancing

What is an example of an extraneous variable?

Extraneous variables within a human population in research can include intelligence levels, gender, or age. When it comes to situational extraneous variables it could include lighting or noise in the setting that impacts results. 

References

Bevans.R. Understanding types of variables. Scriblr. Published on November 21, 2019 Retrieved 18th Feb 2022. https://www.scribbr.com/methodology/types-of-variables/

McLeod, S. A. (2019, July 30). Extraneous variable. Simply Psychology. www.simplypsychology.org/extraneous-variable.html

Stephanie Glen. “Extraneous Variable Simple Definition” From StatisticsHowTo.com: Elementary Statistics for the rest of us! https://www.statisticshowto.com/extraneous-variable/

Extraneous Variable: Definition & Examples. Statology. Retrieved on 18th Feb 2022.https://www.statology.org/extraneous-variable/

Extraneous Variables: Types, Examples and How To Control Them. Indeed. Retrieved on 18th Feb 2022. https://www.indeed.com/career-advice/career-development/extraneous-variable

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