What Is a Control Variable? Definition, Examples, and Importance

This blog compiles every necessary detail that you must know about the control variables. Everything is outlined in this guide, from the importance of these variables to mistakes that researchers make while using control variables. Keep reading to learn more! 

Imagine you are conducting your microbiological experiment, and it is the day of jotting down the results after placing your sample in the furnace for 3 days. You are certain to get your desired results. You enter the laboratory with a coffee mug in hand, walking toward the furnace with enthusiasm. But when you reach you are shocked. Your furnace temperature was changed from the required temperature, distorted your desired results.

If you focus on this story, you will learn that the most important variable for this experiment is temperature, which you have to keep constant. This is what we are going to discuss in this blog: the control variable. Considering this variable is essential to approving a hypothesis and protecting the study from bias. 

Do you know what controlling variables are? Most probably not, because if you knew, you would not be here reading this blog. That’s why the experts at The Academic Papers UK will explain this variable in this guide.

Let’s get started by knowing what a controlled variable is in an experiment and research.

What Is a Control Variable in Research?

The American Psychological Association defines the control variable as “a variable that has a particular effect on the results, but the researcher has no particular interest in it. To overcome its effects, this variable is kept constant during the experiment.”

A variable held constant or limited during a scientific study is known as the control variable. Keeping such a variable constant is necessary for a research study. It is because although it is not of interest to research aims, it can still influence the outcomes or results of the study. 

As a researcher, you always try to keep such a variable constant using different techniques. Also, to determine the exact relationship between dependent and independent variables, it is necessary to control any extraneous variables that can harm the study.

Most teachers assign students assignments on these variables so they can better understand how to manage them while conducting their research during higher degree programs. However, many students from them cannot distinguish between controlled and independent variables and end up writing a weak assignment. They can avail themselves of assignment writing services from The Academic Papers UK to ensure successful assignment writing. 

Why are Control Variables Important?

Although it is not related to the research aims, it can still have a significant impact on the results of a scientific study. This is exactly why controlling such a variable is necessary. However, it is just one point that explains its importance. Some other points are given as follows:

• It allows you to measure the exact relationship between independent and dependent variables.
• Another point that shows its importance in a research study is that if you do not control extraneous variables, your results may be faulty.
• Having an idea of such variables and how to control them allows you to reproduce the experiment.
• Control variables are extremely crucial. It is because they enhance the internal validity of your research study and make the results more valid.

Using The Control Variable in Different Research Studies

After reading the information above, you now have a good idea of what it is and why it is important. Now, we will look at its usage in different research studies, e.g., experimental and non-experimental. Hence, without wasting any time further, let’s see how they are used and how they affect the results of a scientific study.

1. In Experimental Studies

In experimental research studies, you aim to measure the effect of the independent variable on the dependent variable. For this, you manipulate the independent variable and see what changes the manipulation brings to the dependent variable. 

Such variables in experimental studies make sure that the results are fair and free from any kind of bias. How? It is because you can control the extraneous variables in the lab and can minimise their impact to a large extent.

2. In Non-Experimental Studies

Any study that does not involve the use of experiments and makes use of techniques like observation is non-experimental. A control variable plays a crucial role in non-experimental studies. 

This is because, in observational studies, you cannot manipulate the independent variable control. It is not under your control. However, you can monitor its effect on the results and keep it to a minimum level.

Some Examples of Control Variables

Anything you can measure about the research study which is neither related to the independent variable nor the dependent variable is a control variable. The information given above must have strengthened your theoretical knowledge about such a variable. 

Now, let’s strengthen the practical knowledge. Hence, some top examples are as follows:

3 Key Differences Between Control Variables and Control Groups

Many researchers like you confuse the term control variables with control groups. For your information, both controls are different from each other. This is because control groups are mostly governed by constant variables. 

In simple words, you can say the control group is a mini-sub-sample. Do you know about the differences that exist between them? No. Thus, below are the major differences between a control group and a control or constant variable:

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The Difference in Consistency

The first difference that exists between this variable and the control group is the difference in consistency. Such variables remain constant during the whole study. As a researcher, you do not try to manipulate because the internal validity depends on them. On the other hand, control variables govern the control groups. They may change depending on the variables.

The Difference in the Creation

The second difference is related to the method of creation of such variables and groups. Control variables are derived from the research questions formulated at the start of the study. They do not depend on the sample population or respondents. In the meantime, control groups are dependent on the population. The groups are only created by considering the population.

The Difference in the Purpose

Lastly, the 3rd difference that lies between control or constant variables and groups relates to the purpose. Both serve different purposes in a research study. The control variables explain a base value for the measurement of the relationship between independent and dependent variables. On the other hand, the control groups develop a frame of reference for other samples. Thus, both controlled variables and groups are on different missions.

During the academic journey, science students have to write their coursework on the control variable and the key difference between control and other types of variables. However, sometimes, students find it hard to write on these intricate variables. In this scenario, they can get coursework writing services from experts to ensure the successful completion of their academic documents.

3 Methods To Control a Variable in A Scientific Study

There are different methods in practice to control a variable when studying a particular topic. However, three methods are very commonly used. Do you have an idea of those three methods? Most probably not. Thus, a brief description of those three methods is given as follows:

1. Random Assignment

The first method of controlling a variable is known as random assignment. This method is mostly used in experimental studies to control a variable. Furthermore, this method of controlling a variable is particularly useful when there are multiple groups. 

Each group’s participants have different characteristics. Random assignment helps you balance the properties of groups and control variables effectively.

2. Statistical Controls

Sometimes, controlling all the variables and removing their influence on the results is impossible. It mostly happens in non-experimental studies, where a control variable is not in your hands. In such a case, you can apply the technique of statistical control to limit the research bias. 

This method works by applying modelling, weighting, and averaging techniques. Thus, the use of this technique provides you with a more realistic picture.

3. Standardised Procedures

Lastly, the next technique to control a variable is known as standardised procedures. It works on the same principle as a daily routine of a human. This method asks you to use a standard procedure for all the groups involved in the study. 

As the researcher, you must not use one method to study one group and a different method to study the second group. The experimental procedure and method must be the same for every group.

How to Identify the Control Variables in Research?

To identify the control variables in research, you have to spot the factors that can slip in during the experiment and manipulate the results. Have a look at how you can identify these variables:

• First, make a clear research plan and define what you are analysing (independent variables) and what you are measuring (dependent variables). For instance, if you are investigating how various fertilisers affect the growth of the plant, in this scenario, fertiliser is your independent variable, and the plant is your dependent.
• Now, think about all the probes that can impact the results of your plant growth. In the above example, you have to identify all the factors that impact plant growth, such as sunlight, humidity, water, and more.
• After identifying these variables, take a close look and point out which one you can control. In the above example, you can control the amount of sunlight and water for plant growth. 

How to Get Control of an Experiment?

Taking control of scientific research solely depends on the independent variables that are being tested. For instance, if you are testing a new medication, then there is no role of the control group in it. But if you are studying the impact of sunlight on the growth of the plant, then the control group of plants is being investigated.

Follow the steps below while performing scientific research using a control group.

• No matter what type of experiment you are conducting, it always starts with a question that needs an answer. This question is your hypothesis, which sets the stage for your experiment and guides you to figure out what factors you are going to control.
• Once you have crafted a question that you are going to answer with your experiment, you should make your observation, for instance, if you are a medical student and trying to identify the effects of a specific exercise on arthritics patients. For this, you also have to observe the effects of this exercise on patients having no arthritis. This will help you in identifying independent variables and dependent variables.
• On the basis of the collected data from your observations, refine your hypothesis. This step will help you to evaluate the exact independent variables for your experiment. For instance, if you observed that spending time outside the home is beneficial for patients, then your hypothesis would be that spending time outside the home has positive impacts on health.
• Various variables play a crucial role in scientific research. However, an experiment is only conducted by examining one variable at a time, so you have to select only one variable at a time. In this way, you will be able to trace back all the evidence for one specific cause. For instance, if you want to observe the impact of one exercise on all patients. Ensure that they all perform the same action in the same manner at the same time.
• Now, it's time to pick a control group with the same condition. Choosing a control group is the baseline of your experiment. For instance, at this stage, you have to choose a group of patients with the same condition as the experiment group, but who received either no treatment or an unusual treatment. Now, study the effects of the control group and compare it with the experimental group.
• Now that you have picked the experimental and control groups, it’s the right time to start your experiment. To make your experiment successful, you have to be careful in the selection of your experiment and control group. With the right selection, you will certainly meet scientific research standards. For instance, if your hypothesis was that time spent outside the home could improve health, then it is good that your experimental and control groups have the same symptoms.
• Your experiment doesn’t end at the first test, but it might happen that after the first test, you would find that there are no measurable changes that help you to prove your hypothesis. Now, look at any variable that you did not account for in your previous test and conduct your experiment again. Continue this process with the same group and condition until you get the required results. 

3 Common Mistakes that Researchers Make While Handling Control Variables

Imagine a college student who aims to win his science project fair by testing the impact of sunlight on plant growth. But despite his best efforts, he was not able to get the desired results. Do you know the reasons? We tell you the actual reason behind this failure is that the student mishandled the controlled variables, which are the backbone of any research project.

Keep reading to explore the common mistakes that students make when handling these variables.

1. Ignore the Important Variables

One of the biggest mistakes that students make when using the variable in their research project is not identifying all the relevant control variables. They are too focused on dependent and independent variables that they completely overlook the external factors that can significantly impact the results.

How to Overcome It?

To avoid this mistake, students need to consult with their professors and get guidance to identify all the possible factors. Additionally, they have to conduct in-depth research before even starting the experiment.

2. Unable to Monitor Variables Consistently

For a successful conduct of the experiment, it is not enough to just identify the control variables; they must also monitor these variables throughout the experiment. For instance, if you are analysing the effect of light on plant growth, it is essential to check all the plants.

How to Avoid It?

To overcome this mistake, you have to ensure that you check your experiment from time to time to see the results. If your experiment is long and continues for two or three days, you can set a reminder on your phone to make sure you don’t forget to check the results.

3. Incomplete Documentation

Another mistake that researchers make when handling the control variables is inconsistent documentation. If you control your variables effectively but fail to maintain documentation, then you will not get your desired experimental results.

How to Overcome?

You can use the software to document all the results that you have obtained from your experiment. In this software, you can list all the control variables, current results, and all the possible changes that come with time. 

Final Thoughts

Scientific research is not about just changing one factor and getting the required results. There are many variables that you must take into account while conducting your experiment. The control variable is one of them. This variable is kept constant throughout the experiment, so it doesn’t affect the desired results.

In this blog, we have shared everything about this variable, from its importance to the method to control the experiment. We hope that this guide will help you to better understand this variable for conducting the research for your dissertation writing. If you are still confused about it, you can avail yourself of dissertation writing services from The Academic Papers UK to ensure the successful completion of your thesis. 

FAQs

What Is a Control Variable?

Simply put, it is a variable in a research study that is held constant. It does not have any relation to the research aims and objectives. However, it is a variable that has the potential to harm the outcomes of the research study. Therefore, the researchers keep this variable constant so it doesn’t affect the desired results. 

Why Do We Control Variables?

Control variables enhance the validity of the research study. Also, they make sure that the results obtained after the study are not faulty and answer the research questions. Additionally, a researcher only wants to investigate the effects of independent variables on the dependent variables. The control variables enable them to get the desired results by experimental manipulation without any external interruption.

For instance, if you want to investigate the impact of Vitamin A on the improvement of the mindfulness. You have to design an experiment with two groups: one is the control group taking placebo pills, and the other is the experimental group receiving the supplement.

The addition of Vitamin A in the diet is the independent variable, and its impact on mindfulness is the dependent variable. To observe the effect of Vitamin A, you have to keep other factors constant, including:

• Screen time
• Diet
• Caffeine dose
• Timing of meals

What Is Internal Validity?

Internal validity is the extent to which you are confident that the relationship between the variables cannot be described by other factors. Internal validity and control variables have a close relationship. The more you control them in the study, the more its internal validity. So, this is what the term internal validity means.

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