Basics of Research Process

Extraneous Variable: Full Guide + Examples

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An extraneous variable is something outside the research study that could potentially skew the results. It's not the main factor that reserchers are studying, but it can still affect the dependent variable. These variables are often not controlled, and if not accounted for, they can lead to incorrect conclusions. Therefore, researchers should recognize and control for extraneous variables to ensure their findings are valid.

In this blog post, you will get acquainted with a detailed definition of extraneous variable, its peculiar traits, and difference from other variables. A special experiment was conducted to show how extraneous variables affected study in general. Examples are given so you can better understand how extraneous variables may distort the study results.  

Extraneous Variable Definition

To start with, it should be defined what are extraneous variables. If you ask any dissertation writer, since this type of variable is one that may affect the relationship between the independent (controlled and manipulated by an experimenter) and dependent (measured by an experimenter) determinants, they can affect the results of an experiment. These factors have nothing in common with independent ones. Extraneous variables influence research by affecting the dependent variable.

In other words, extraneous variables belong to any kind of variables that a student is not intentionally studying in their test or experiment. Student, running an experiment, sees whether one has a particular effect on others. They strongly influence/affect the results of the study. Since an extraneous variable is something that you are not investigating, or an uncontrolled piece, it can lead to wrong conclusions.  

Importance of Extraneous Variables

Extraneous variable in research shows itself as an integral part of the whole experiment. To achieve goals of an experiment, students need extraneous variables which shape process in such a way that identifying goal settings is easy. Goals’ achievements are shown in different ways, but control of extraneous variables is essential for making results those what was expected.

The experimenter chooses valid methods. The process can’t be uncontrolled. Results must be those which were set from the beginning. Experimenters should see the finishing picture from the early steps of the experiment. It’s natural that some new points interfere in the process and cause a new course of events, so unexpected effects occur.  

Extraneous Variable vs. Confounding Variable

Extraneous variables have to deal with two parameters that are not causally related. Association is produced in a free way. For example, we have two variables that have an association between them caused by an effect of a third factor. In that case, we can claim that the relationship between these two variables is false since they were affected by that factor which we will call an extraneous variable.

What concerns confounding variables, they are pretty similar to extraneous ones. The main difference is that they affect two factors that are not related spuriously. For example, if one factor affects another and they are both casually related, their association can also affect the third factor. Since the first two are exaggerated and affected by the third factor, In this case, we would call this third factor a confounding variable.

Both have associations with independent and dependent ones, in other words – causal relationships. It affects the way the experiment is being held. For a better understanding of the difference between extraneous and confounding variables, it would be great to give an example.

An extraneous variable gives an example with a participant who performs a memory test being tired. This situation strongly influences results. Confounding ones give an example, association with food: how much people eat. Whether lack of exercise or large portions influences weight gain. Fact should be taken into account that men eat more than women.  

Examples of Extraneous Variables

For successful research, an extraneous variable example is a must. It helps better understand the main peculiarities. Below, most essential info concerning types and examples is given. But before students determine with research question needed, it would be nice to look at the next examples:

  • Memory capacity and test performance: level of stress, anxiety, time of the day.
  • Driving ability/sleep deprivation: noise, experience, road condition.

The outcome is determined by question answering. Providing their own experiment, students might make use of examples and use them for reference.

So, let’s consider the situation where you run an experiment on the impact of stress on test performance. In this case, stress will be an independent factor, when scores of a test performance - dependent one. But what can also affect a relationship between independent and dependent ones? There are a lot of other factors such as gender, age, knowledge, physical and mental state, mood, environmental conditions that may have an impact on the results of your experiment. These factors are called extraneous variables and should be noted by an experimenter so this effect on results can be controlled. Read more about a controlled experiment in one of our blogs.

Types of Extraneous Variables

Different researches need peculiar methods. For better studying conditions, there were constructed 4 main types of extraneous variables:

  1. Situational characteristics.
  2. Demand characteristics.
  3. Experimenter effects.
  4. Participant characteristics.

Every peculiar one needs a different control method. Every type has special demands, characteristics, and peculiar features. All essential notions are depicted below. Students might make use of them to shape their own professional experiment.

Situational Extraneous Variables

This category includes different environmental conditions which strongly influence the outcome. They are called a situational variable. To eliminate extraneous characteristics means to guarantee accurate results. All participants should have equal conditions.

A fine example: an interviewer makes talk shows while several participants are affected by negative environmental factors such as noise. It might be caused by people or strong wind. This takes away their concentration. They become annoyed or distracted and, as a result, can’t give exact answers. Statistics show that if some of the participants feel hot or cold, it negatively influences correct answers. If a participant takes a test in a cold room, the temperature will be considered an extraneous situational factor.  

Demand Extraneous Variables

Demand characteristic describes peculiar cues in experimental study design. These influence participants’ natural answers in an unintentional way, how they behave. Demand characteristics could manifest in a row of different ways if researchers are not cautious when proceeding and designing with the study.

To describe demand variables in another way, a fine example is given: participants already know the results of an experiment. Their concentration is not on the highest level because there is no need to think hard (results are already known). Participants might give incorrect answers (for no purpose, just unintentionally). So, final expectations might differ from those suggested earlier.  

Experimenter Extraneous Variables

These are the ones that are controlled and manipulated by the experimenter. Experimenter variables have three types suggested: independent, dependent, and controlled. The experimenter makes all options. Independent ones are those experimenter changes or manipulates. This has a strong effect on a dependent type.

A fine example is related to controlled type. It influences such measures as temperature. This is a much common type. Why? Temperature is thought to be controlled if it is held constant during an experiment. An investigator should take into account this fact. Feeling the subject subtly helps a researcher give correct analysis. Experimenter extraneous effects are also when an experimenter unintentionally gives cluses for how participants should behave.  

Participant Extraneous Variables

These could be defined as different features of an individual that might impact the way a participant reacts/answers an experiment. Fine examples of participant variables consist of: mood, literacy status, socioeconomic status, ethnicity, age, gender, clinical diagnosis, etc. These ones could be considered extraneous because they influence results though an experimenter is not studying. A statement is closely tied with these questions:

  • How can participants affect different study results?
  • Which factor is easier to control? Why?
  • Why intelligence, background, personality, and motivation are taken into account?

Remember that each person differs from another. Research conditions vary as well. Experimental design differs due to conditions. Every example is individual. If you would like to know more about different types of research design, read one more blog.

How to Control Extraneous Variables

Experts distinguish four main methods of controlling extraneous variables. These are:

  1. Random sampling.
  2. Standardized procedures.
  3. Counterbalancing.
  4. Masking.

Every type has peculiar features. Masking has a relation to an experimenter factor. Often it is called the double-blind method. A key factor is in asking somebody for experiment administration. But a person is unaware of a research purpose. Counterbalancing has to deal with two groups. First is asked to complete «step one», another – «step two». It has a close touch with participant factors. Standardized procedures have a direct connection with demand characteristics and situational parameters. Random sampling provides participants with the ability to be equally chosen. Should you have any trouble, buy research paper online tailored personally for you.

Final Thoughts on Extraneous Variable

Writing an academic paper is not an easy task. Students should have fine knowledge, practice, and the ability to represent their thoughts correctly. There exist different ways to control the influence of extraneous variables. Every has peculiar features, distinguishing characteristics. To determine what is what, students have to learn and study a lot. An incorrect material presentation might reduce experiment value. Be aware of it.  

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Frequently Asked Questions

1. What is the best method to control extraneous variables?

No universal method is suggested. A particular one depends on participants and conditions. Every method deals with peculiar features and is needed in particular situations. For instance, situational characteristics might deal with weather conditions, while participant parameters deal with personal feelings/mood. Controlling extraneous variables include testing participants but in a different way. Conditions vary due to peculiar situations.

2. How to control extraneous variables in nursing research?

Two essential points strongly influence research results – gender and age. Random sampling is practiced to reduce impact. Control for extraneous variables in nursing research differs according to personal peculiarities. Different age/gender groups cope with tasks in peculiar ways. Experimental research (its types/methods) differs due to these factors.

3. How can extraneous variables impact an experiment?

If being left uncontrolled, extraneous factors could conduct inaccurate derivations. The impact of extraneous variables on experiment is closely connected with affected outcomes. Extraneous factors also influence the validity of a research (choose actual topics).

4. Can I use standardized procedures to eliminate both situational and demand variables?

Yes, you can. Standardized procedures deal with demand characteristics and situational variables. These take place during study designing. To avoid demand and situational variables from study outcome influence, instructions exist. The use of deception helps to eliminate an effect. The same statement refers to standardizing a procedure. To eliminate situational factors, similar questions are coped with.

Article posted on:May 10, 2022
Article updated on:May 11, 2023


Leave your comment here:
6/25/2022 9:47 AM
I really liked the article. Thanks for sharing the tips on how to control an extraneous variable. But I'm still wondering, are there any cases when you can't control an extraneous variable?
6/25/2022 11:47 AM
Hi Ethan,

Yes, sometimes it may be difficult to control for an extraneous variable. For example, while it's quite easy to keep the same lighting or temperature indoors, it will be much more difficult to do that outdoors. In this case, it's better to run an experiment where these factors can be easily controlled.
7/7/2022 8:27 AM
Hi! Can you give some examples of an extraneous variable in Psychology? I'm planning to determine how an emotional state influences focus and concentration. I would really appreciate your timely help.
7/7/2022 9:00 AM
Hi Kathie,

In your case, it can be any external factor that can also affect concentration. For example, such conditions as the age, time of an experiment, hours of sleep or personal traits can be extraneous variables.