A mediating variable is a factor that explains the process through which an independent variable affects a dependent variable.
Here is a scholarly definition from Veronica Hefner (2017):
“A mediating variable is a variable that links the independent and the dependent variables, and whose existence explains the relationship between the other two variables. A mediating variable is also known as a mediator variable or an intervening variable.”
For example, in a study exploring the link between exercise and mental well-being, self-esteem might serve as a mediating variable, meaning that exercise boosts self-esteem, which then enhances mental well-being. It is that hidden ‘middle step’.
Mediating Variable Examples
1. The Link Between Social Media Usage and Loneliness
Independent Variable: Social media usage
Dependent Variable: Feelings of loneliness
Mediating Variable: Quality and frequency of face-to-face interactions
If social media usage reduces the amount or quality of face-to-face time with others, it can lead to feelings of loneliness. Therefore, the relationship between extensive social media usage and feelings of loneliness might be mediated by the diminished quality and frequency of in-person interactions.
2. The Link Between Physical Activity and Mental Health
Independent Variable: Physical activity
Dependent Variable: Improved mental health
Mediating Variable: Endorphin release
When an individual engages in physical activity, the body releases endorphins, which are known as “feel-good” hormones. These endorphins play a significant role in enhancing mood and reducing feelings of anxiety and depression. Therefore, the positive relationship between physical activity and improved mental health might be mediated by the release of endorphins.
3. The Link Between Sleep Duration and Academic Performance
Independent Variable: Sleep duration
Dependent Variable: Academic performance
Mediating Variable: Cognitive function and attention span
Adequate sleep duration is crucial for optimal cognitive functioning and attention span. When students get adequate sleep, their cognitive abilities like memory, decision-making, and problem-solving are enhanced, leading to better academic performance. Thus, the relationship between sleep duration and academic performance might be mediated by improvements in cognitive function and sustained attention span.
4. The Link Between Job Satisfaction and Employee Turnover
Independent Variable: Job satisfaction
Dependent Variable: Employee turnover
Mediating Variable: Organizational commitment
Employees who are satisfied with their job are more likely to develop a stronger commitment to their organization. This commitment often results in greater loyalty and a decreased likelihood to leave the company. Therefore, the relationship between job satisfaction and reduced employee turnover might be mediated by the increased sense of organizational commitment.
5. The Link Between Dietary Habits and Physical Health
Independent Variable: Dietary habits
Dependent Variable: Physical health
Mediating Variable: Nutrient intake
If someone consistently consumes a balanced diet, they intake essential nutrients that promote good health. The relationship between dietary habits and physical health might be mediated by the level of essential nutrients consumed, ensuring proper body function and preventing deficiencies.
6. The Link Between Classroom Environment and Student Engagement
Independent Variable: Classroom environment
Dependent Variable: Student engagement
Mediating Variable: Student’s perception of safety and belonging
A positive and inclusive classroom environment can make students feel safe and like they belong. When students perceive that they are in a safe environment where they are valued, they are more likely to engage actively in learning. Thus, the relationship between the classroom environment and student engagement might be mediated by the student’s feelings of safety and belonging.
7. The Link Between Work-Life Balance and Employee Burnout
Independent Variable: Work-life balance
Dependent Variable: Employee burnout
Mediating Variable: Stress levels
Employees with a poor work-life balance often experience heightened stress levels due to the overlapping demands of their job and personal life. Elevated stress levels over extended periods can lead to feelings of burnout. Therefore, the relationship between work-life balance and employee burnout might be mediated by the levels of stress an employee experiences.
8. The Link Between Urban Green Spaces and Mental Well-being
Independent Variable: Presence of urban green spaces
Dependent Variable: Mental well-being
Mediating Variable: Frequency of nature interactions
When urban areas have more green spaces, residents tend to interact more frequently with nature, either by walking, exercising, or simply spending time in these areas. These interactions with nature have been shown to reduce stress and increase feelings of relaxation. Therefore, the relationship between the presence of urban green spaces and mental well-being might be mediated by the frequency of nature interactions.
9. The Link Between Employee Training and Job Performance
Independent Variable: Employee training
Dependent Variable: Job performance
Mediating Variable: Skill acquisition and competence
Regular and quality employee training sessions equip employees with new skills and enhance their competence in their roles. As they become more skilled and competent, their performance at their job tends to improve. Thus, the relationship between employee training and job performance might be mediated by the level of skill acquisition and competence achieved.
10. The Link Between Plant Ownership and Reduced Stress
Independent Variable: Plant ownership
Dependent Variable: Reduced stress
Mediating Variable: Increased interaction with nature and nurturing behavior
Caring for plants allows individuals to interact with nature even in indoor environments. Additionally, the act of nurturing plants and seeing them grow can be therapeutic and rewarding. These interactions and behaviors can lead to relaxation and a reduction in stress levels. Therefore, the relationship between plant ownership and reduced stress might be mediated by the increased interaction with nature and the nurturing behavior associated with plant care.
11. The Link Between Music Lessons and Cognitive Development
Independent Variable: Music lessons
Dependent Variable: Cognitive development
Mediating Variable: Development of discipline and concentration
Engaging in music lessons often requires students to practice regularly, fostering discipline. Additionally, mastering an instrument necessitates concentration and focus. These attributes can positively impact other areas of life, including academic pursuits. Thus, the relationship between music lessons and cognitive development might be mediated by the enhanced discipline and concentration developed through musical practice.
12. The Link Between Outdoor Play and Physical Health in Children
Independent Variable: Outdoor play
Dependent Variable: Physical health in children
Mediating Variable: Physical activity levels
Children who engage in outdoor play are often more physically active than those who spend more time indoors, as they run, jump, climb, and engage in other physical activities. This increased level of physical activity is essential for cardiovascular health, muscle development, and overall physical well-being. Therefore, the relationship between outdoor play and physical health in children might be mediated by the levels of physical activity they engage in.
13. The Link Between Personal Financial Management and Life Satisfaction
Independent Variable: Personal financial management
Dependent Variable: Life satisfaction
Mediating Variable: Financial security and reduced monetary stress
Individuals who effectively manage their finances tend to achieve a higher degree of financial security. This security can alleviate stress and anxiety related to monetary concerns, leading to a more content and satisfied life. Thus, the relationship between personal financial management and life satisfaction might be mediated by the sense of financial security and reduced monetary stress achieved through effective financial practices.
14. The Link Between Reading Habits and Vocabulary Size
Independent Variable: Reading habits
Dependent Variable: Vocabulary size
Mediating Variable: Exposure to diverse words and contexts
Individuals who read regularly encounter a wide variety of words in different contexts. This repeated exposure enhances their vocabulary as they come across and internalize new words. Therefore, the relationship between reading habits and vocabulary size might be mediated by the degree of exposure to diverse words and contexts through reading.
15. The Link Between Community Involvement and Personal Well-being
Independent Variable: Community involvement
Dependent Variable: Personal well-being
Mediating Variable: Sense of belonging and purpose
Engaging with and contributing to one’s community can foster a sense of belonging and purpose. Feeling connected and knowing that one’s actions positively impact others can lead to enhanced personal well-being. Thus, the relationship between community involvement and personal well-being might be mediated by the heightened sense of belonging and purpose derived from active community participation.
Mediating vs Moderating vs Confounding Variables
Mediating, moderating, and confounding variables are three of the most common types of ‘third variable‘. They are similar in that they need to be observed or controlled in order to better understand the relationship between the independent and dependent variables (Stapel & van Beek, 2015).
However, the three differ in important ways.
Let’s start with some definitions:
- Mediating Variables: These explain the process through which an independent variable influences a dependent variable.
- Moderating Variables: These influence the strength or direction of the relationship between an independent and a dependent variable (Nestor & Schutt, 2018).
- Confounding Variables: These are external factors that, if not controlled, can cause a false perception of a relationship between the independent and dependent variables (Boniface, 2019).
The table below shows how they differ:
|Aspect||Mediating Variables||Moderating Variables||Confounding Variables|
|Definition||Explains the process or mechanism through which the independent variable affects the dependent variable.||Affects the strength or direction of the relationship between the independent variable and dependent variable.||An external factor that is related to both the independent variable and dependent variable, potentially creating a false impression of a direct relationship between the two (Scharrer & Ramasubramanian, 2021).|
|Role in Research||Helps clarify how or why one variable affects another.||Helps clarify under what conditions or for whom the independent variable affects the dependent variable differently.||Introduces bias or distortion in the observed relationship between independent variable and dependent variable if not controlled.|
|Example||Studying the effect of training on job performance, where self-confidence (mediator) increases with training and leads to better performance.||Studying the effect of training on job performance, where the relationship might be stronger for those with prior related experience (moderator).||When examining the relationship between exercise and health, diet (confounder) can influence both exercise habits and health, potentially distorting the observed relationship.|
Boniface, D. R. (2019). Experiment Design and Statistical Methods For Behavioural and Social Research. CRC Press. ISBN: 9781351449298.
Hefner, V. (2017). Variables, Moderating Types. In Allen, M. (Ed.) The SAGE Encyclopedia of Communication Research Methods. SAGE Publications.
Nestor, P. G., & Schutt, R. K. (2018). Research Methods in Psychology: Investigating Human Behavior. SAGE Publications.
Scharrer, E., & Ramasubramanian, S. (2021). Quantitative Research Methods in Communication: The Power of Numbers for Social Justice. Taylor & Francis.
Stapel, B. & van Beek, R.J. (2015). Confounders, moderators and mediators. In Mellenbergh, G. J., & Adèr, H. J. (Eds.). Advising on Research Methods: Selected Topics 2014. Johannes van Kessel Advising.
Dr. Chris Drew is the founder of the Helpful Professor. He holds a PhD in education and has published over 20 articles in scholarly journals. He is the former editor of the Journal of Learning Development in Higher Education. [Image Descriptor: Photo of Chris]