Independent Variables, Dependent Variables, And Extraneous Variables.
Compare independent variables, dependent variables, and extraneous variables. Describe two ways that researchers attempt to control extraneous variables. Provide an example of how this is applied using a peer-reviewed, primary research article.
Sample Solution
In research, understanding the relationships between variables is crucial to drawing meaningful conclusions. Independent, dependent, and extraneous variables play distinct roles in this process.
Independent Variables:
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Controlling Extraneous Variables:
Researchers employ various strategies to minimize the influence of extraneous variables, ensuring the validity and reliability of their findings. Here are two common methods:
- Definition: The variable manipulated by the researcher to determine its effect on another variable.
- Characteristics:
- Controlled and manipulated by the researcher.
- Can be quantitative or qualitative.
- Examples: Dose of medication, type of teaching method, presence or absence of a specific stimulus.
- Definition: The variable measured to observe the effect of the independent variable.
- Characteristics:
- Responds to changes in the independent variable.
- Measured and observed by the researcher.
- Examples: Learning outcomes, test scores, physiological responses, behavior changes.
- Definition: Variables other than the independent and dependent variables that can influence the outcome of a study.
- Characteristics:
- Not manipulated or controlled by the researcher.
- Can affect both the independent and dependent variables.
- Can introduce bias and distort results.
- Examples: Participant characteristics (age, personality), environmental factors (noise, temperature), experimenter bias, research design limitations.
| Feature | Independent Variable | Dependent Variable | Extraneous Variable |
| Definition | Manipulated | Measured | Uncontrolled |
| Role | Cause | Effect | Interference |
| Control | Researcher | Researcher | Limited or none |
| Example | Exercise intensity | Weight loss | Participant's diet |
- Randomization:
- Participants are randomly assigned to different groups, ensuring equal distribution of extraneous variables across groups.
- This minimizes the chance that any one group will have a systematic advantage or disadvantage due to extraneous factors.
- Matching:
- Participants are matched on relevant characteristics (age, gender, education level) to create groups with similar baseline conditions.
- This reduces the influence of extraneous variables that are not controlled by the research design.
- Independent Variable: Type of music therapy (relaxing music vs. upbeat music).
- Dependent Variable: Pain perception measured by a self-reported pain scale.
- Extraneous Variables: Patient age, gender, severity of burns, pain medication use.
- Randomization: Burn patients were randomly assigned to either the relaxing music or upbeat music group.
- Matching: Groups were matched on age, gender, and severity of burns to minimize initial differences in pain perception.
- Additional Controls: Participants were instructed to refrain from taking pain medication during the study period. The research environment was standardized to minimize noise and other distractions.