Research Designs: Ex-post facto and Experimental
📘 3.4 Research Designs: Ex-post facto and Experimental (अनुत्पादक एवं प्रायोगिक अनुसंधान रूपरेखाएँ)
🧠 What is a Research Design?
A research design is the blueprint or framework for conducting a study. It outlines:
- How data will be collected
- What variables are involved
- How relationships between variables will be tested
- Whether cause-effect can be established
The two major types of designs in this topic are:
- Ex-post facto
- Experimental
🔍 I. Ex-Post Facto Research Design (पूर्व प्रभावोत्तर अनुसंधान)
📌 Definition:
“Ex-post facto” means “after the fact.”
It is used when the independent variable (IV) has already occurred and cannot be manipulated ethically or practically.
👉 The researcher examines the effects of an IV after it has already happened.
🔧 Key Features:
- No manipulation of variables
- IV is not under researcher control
- Relies on group comparisons or statistical controls
- Correlation ≠ Causation
✅ Advantages:
- Ethical (useful when manipulating IV would be unethical)
- Useful in studying naturally occurring variables (e.g., trauma, gender, caste)
❌ Limitations:
- No control over extraneous variables
- Cannot establish definitive causality
- Prone to confounding variables
📚 Example:
A psychologist wants to study whether childhood trauma is linked to adult depression.
Since trauma can’t be ethically imposed, participants who have already experienced trauma are compared with those who haven’t.
🇮🇳 Indian Context Example:
- Studying the impact of caste-based discrimination on academic performance in Dalit students.
- Analyzing effects of COVID-19 lockdown on mental health — the lockdown is a naturally occurring IV.
- Comparing stress levels between students from rural vs. urban schools.
🧪 II. Experimental Research Design (प्रायोगिक अनुसंधान)
📌 Definition:
Experimental design involves the deliberate manipulation of an independent variable to observe its causal impact on a dependent variable.
👉 The gold standard for establishing cause-and-effect relationships.
🔧 Key Components:
| Element | Description |
|---|---|
| Independent Variable (IV) | Variable that is manipulated (e.g., amount of sleep) |
| Dependent Variable (DV) | Variable that is measured (e.g., attention level) |
| Control Group | Group that does not receive the experimental treatment |
| Experimental Group | Group that receives the treatment |
| Random Assignment | Participants are randomly assigned to groups |
✅ Advantages:
- High internal validity
- Can establish causality
- Control over confounding variables
❌ Limitations:
- May lack external validity (real-world applicability)
- Can be ethically restrictive
- Artificial setting may affect behavior
📚 Example:
To test if meditation improves focus, researchers assign:
- Group A: 15 min daily meditation
- Group B: No meditation
Then test attention scores after 4 weeks.
🇮🇳 Indian Context Example:
- A CBSE school pilot project tests whether value education classes reduce bullying behavior.
- AIIMS study on how yoga vs. physical exercise impacts depression levels in teenagers.
- Experimental trials in ISRO’s space psychology labs studying sleep-deprivation in simulated missions.
⚖️ III. Comparison Table: Ex-Post Facto vs Experimental Design
| Feature | Ex-post Facto | Experimental |
|---|---|---|
| IV Manipulated? | ❌ No | ✅ Yes |
| Causality? | ❌ Cannot be conclusively inferred | ✅ Can establish cause-effect |
| Control Group? | Sometimes | Always |
| Ethical Flexibility | High | Sometimes limited |
| Example | Trauma → Depression | Meditation → Focus |
| Indian Use Case | Study of exam pressure effects | Yoga vs control group on anxiety |
🧠 Tip for UPSC Mains
When writing answers:
- Define both types
- Give 1 Indian example each
- Mention suitability and limitation
- Use a comparison table for clarity
✅ Conclusion
Both ex-post facto and experimental designs are essential tools in a psychologist’s research arsenal:
- Use experimental design when you want to test a hypothesis in controlled conditions and can manipulate variables.
- Use ex-post facto design when the variable of interest has already occurred, especially in social, developmental, or clinical psychology.
In Indian psychological research — especially in education, caste studies, gender roles, and mental health — ex-post facto designs are commonly used due to ethical and cultural constraints.
