Deviation IQ, Constancy, and Measurement
📘 10.4 IQ: Deviation IQ, Constancy, and Measurement
🔷 What is IQ?
Intelligence Quotient (IQ) is a score derived from standardized tests to assess an individual’s intelligence level relative to others of the same age group.
🔹 1. Historical Concept: Ratio IQ
- Formula:
IQ=Mental AgeChronological Age×100IQ = \frac{Mental\ Age}{Chronological\ Age} \times 100
- Example:
A child with a mental age of 12 and a chronological age of 10 would have an IQ = 120.
🔴 Limitation: This becomes inaccurate for adults — hence replaced by Deviation IQ.
🔹 2. Deviation IQ
📌 Concept:
- Measures IQ relative to the statistical average performance of the same age group.
- Average IQ is 100, and standard deviation is usually 15.
📊 Example:
- If you score higher than 84% of your peers, your IQ may be ~115.
| IQ Range | Interpretation |
|---|---|
| 130+ | Very Superior |
| 120–129 | Superior |
| 110–119 | High Average |
| 90–109 | Average |
| 80–89 | Low Average |
| <70 | Extremely Low (Intellectual Disability) |
🧠 Tools Used:
- Wechsler Adult Intelligence Scale (WAIS)
- Stanford-Binet Intelligence Scales
🔹 3. Constancy of IQ
📌 Principle:
- IQ remains relatively stable over time once a person reaches adolescence (~age 7–10 onward).
- IQ tests are standardized, so they reflect long-term patterns.
🧠 Practical Implications:
- A child with a high IQ at age 10 will likely continue to score high later.
- However, environmental changes, nutrition, trauma, education can cause minor fluctuations.
📈 Example:
- A rural student may initially score 85 due to poor exposure, but with access to digital learning, this may rise slightly over years — though not drastically.
🔹 4. Measurement of IQ
📚 Common Standardized Tests:
| Test | Target Group | Description |
|---|---|---|
| Stanford-Binet | 2 to adult | Measures fluid reasoning, knowledge |
| WAIS (Wechsler Adult Intelligence Scale) | Adults | Most widely used IQ test |
| WISC (Wechsler Intelligence Scale for Children) | 6–16 | Child IQ across verbal & performance |
| Raven’s Progressive Matrices | Non-verbal test | Culture-fair, often used in India |
| DAS-Naglieri CAS | Children (India-US) | Based on PASS model by J.P. Das |
🛠 Methods Used:
- Verbal reasoning
- Spatial ability
- Memory recall
- Pattern identification
- Logical puzzles
🔍 Indian Context
- NCERT & NIPCCD use IQ assessments to identify gifted and slow learners.
- District Disability Rehabilitation Centres (DDRCs) use IQ tests to classify levels of intellectual disability.
- J.P. Das’s PASS theory is often used for culturally relevant IQ assessments in India.
🧩 Real-Life Examples
- Civil Services Prep:
- Candidates with high fluid intelligence tend to perform better in CSAT reasoning and essay framing.
- School Scenario:
- A child with IQ of 130 is placed in an enrichment program (gifted education).
- Another with IQ of 65 may receive inclusive education with support services.
- Policy Making:
- IQ data is used in mental health policy, NEP 2020 emphasis on learning outcomes, and reservation criteria for specific disabilities.
📌 UPSC Ethics Paper IV Use:
- Case example:
As a DM, you find a tribal school where children are labelled “dull”. Psychometric testing shows low average IQ, possibly due to malnutrition and poor stimulation. Instead of judging, you:
- Recommend nutritional schemes
- Initiate teacher training
- Bring in digital educational tools
This reflects compassion + scientific temper + social responsibility.
✍️ Points for Mains Answer (10 marks)
- Define IQ with historical + deviation view.
- Explain constancy and what can affect it.
- Mention standard tools (Indian + global).
- Give examples from governance/education.
- Conclude with ethical implications of IQ classification.
🧠 Visual Summary
IQ Measurement
├── Ratio IQ (Mental/Chrono Age × 100)
├── Deviation IQ (Statistical average, SD=15)
├── Constancy (Relatively stable after early years)
└── Tools
├── WAIS, Stanford-Binet, WISC
└── Raven's, CAS (India)
