UNDERSTANDING VARIABLES IN RESEARCH
In research—especially in quantitative, qualitative, and mixed methods—the concept of variables is essential for formulating research questions, designing instruments, and interpreting results.
What Is a Variable?
According to Ary et al. (2018), a variable is a characteristic or attribute that can take on different values among individuals or groups.
Creswell (2014) adds that variables are central components of quantitative research, where they are measured, manipulated, or controlled to understand relationships or effects.
In simple terms:
A variable is something that changes or varies.
In qualitative research, the term variable is not commonly used.
Instead, researchers discuss themes, constructs, or categories that emerge from data.
Meanwhile, in mixed methods, variables are used in the quantitative phase, while qualitative constructs help explain variable-related findings.
Types of Variables in Quantitative Research
Based on Role in the Study
|
Type of Variable |
Definition |
Example in Educational Research |
|
Independent Variable (IV) |
A variable that is manipulated or considered the cause |
Teaching method (traditional vs. digital) |
|
Dependent Variable (DV) |
The outcome or result measured |
Students' English test scores |
|
Control Variable |
Variables held constant to prevent them from influencing the results |
Same textbook, same duration of study |
|
Moderating Variable |
A variable that affects the strength or direction of the relationship between IV and DV |
Students’ motivation level affects how teaching method influences test scores |
|
Mediating Variable |
A variable that explains the process through which IV affects DV |
Learning engagement mediates the effect of teaching method on test scores |
Based on Data Characteristics
|
Type |
Description |
Example |
|
Discrete Variable |
Counts in whole numbers |
Number of students in a class |
|
Continuous Variable |
Can take any value within a range |
Test scores, height, time spent studying |
Based on Measurement Scale
1. Nominal: Categories without order
Example: Gender (male/female), Type of school (public/private)
2. Ordinal: Categories with order but unequal intervals
Example: Satisfaction level (low, medium, high)
3. Interval: Ordered, equal intervals, but no true zero
Example: Temperature in Celsius, IQ scores
4. Ratio: Ordered, equal intervals, with a true zero
Example: Weight, test scores, number of words learned
Variables in Qualitative Research
Qualitative research does not manipulate variables. Instead, it explores phenomena through:
• Themes
• Patterns
• Constructs
Example:
In a study on student motivation to learn English, the researcher investigates emerging themes such as fear of making mistakes, teacher support, and peer influence.
2. Variables in Mixed Methods
Mixed methods integrate quantitative variables with qualitative constructs to provide a deeper explanation.
Example:
• Quantitative Phase:
Measures teaching method (IV) and learning outcome (DV).
• Qualitative Phase:
Interviews students to understand why certain methods were effective or ineffective (emerging themes act as explanatory variables).
3. Summary Table:
Treatment of Variables by Research Design
|
Research Design |
Nature of Variable |
Purpose |
|
Quantitative |
Clearly defined, measurable variables |
To test hypotheses and establish relationships |
|
Qualitative |
Uses constructs/themes instead of variables |
To explore meaning and interpretation |
|
Mixed Methods |
Combines variables and themes |
To both measure and explain findings |
4. Examples Across Research Designs
|
Research Topic |
Quantitative Approach |
Qualitative Approach |
Mixed Methods Approach |
|
Vocabulary Learning |
IV: Teaching method,
DV: Vocabulary score |
Themes: Student attitudes and learning experiences |
Quant: test scores;
Qual: interviews explaining outcomes |
Variables are essential to the structure of research. Understanding how variables function across different methodologies helps researchers design robust, meaningful studies.
