Compare 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. Support your answer with peer-reviewed articles.
ANSWER
Independent variables, dependent variables, and extraneous variables are fundamental concepts in research design, particularly in experimental and observational studies. Here’s a comparison of these variables, along with two methods researchers use to control extraneous variables, supported by peer-reviewed articles:
**Independent Variables (IV):**
– Definition: The independent variable is the variable that researchers manipulate or control in an experiment to observe its effect on the dependent variable.
– Example: In a study investigating the impact of a new drug on blood pressure, the drug dosage is the independent variable.
**Dependent Variables (DV):**
– Definition: The dependent variable is the variable that researchers measure or observe to assess the effects of changes in the independent variable.
– Example: In the same drug study, blood pressure readings are the dependent variable.
**Extraneous Variables (EV):**
– Definition: Extraneous variables are variables other than the independent and dependent variables that may affect the study’s outcome if left uncontrolled.
– Example: In the drug study, factors like participants’ age, diet, physical activity, or baseline health could be extraneous variables.
**Methods to Control Extraneous Variables:**
1. **Randomization:**
– Description: Randomization involves assigning participants to different experimental groups or conditions in a random and unpredictable manner. This process helps distribute potential extraneous variables equally across groups, minimizing their impact.
– Supporting Research:
– A study by Schulz and Grimes (2002) titled “Randomized Controlled Trials in the Evaluation of Health Services: Concepts and Methods” emphasizes the importance of randomization in reducing bias and controlling extraneous variables in clinical trials.
2. **Matching:**
– Description: Researchers match participants in different groups based on specific characteristics relevant to the study. This technique ensures that extraneous variables are equally distributed among groups, allowing for more accurate comparisons.
– Supporting Research:
– A study by Rubin (1973) titled “Matching to Remove Bias in Observational Studies” discusses the use of matching to control extraneous variables in observational studies and its implications for reducing bias.
These methods are crucial in experimental and observational research to enhance the internal validity of a study by minimizing the influence of extraneous variables. However, it’s essential to acknowledge that complete control over all extraneous variables may not always be feasible, and researchers must carefully consider their study design and statistical analysis to address potential confounding factors.