📋 Data Sources & Methodology
This page explains exactly how every figure on the India Development Data Explorer is sourced, selected, verified and presented — including which base years apply, how revision cycles work, and where official data has limitations.
1. Source Hierarchy
We use a strict source hierarchy. Higher-ranked sources override lower-ranked ones for the same indicator and period.
| Rank | Source | Used For |
|---|---|---|
| 1 (Primary) | MoSPI / NSO Press Releases (mospi.gov.in) | GDP, GVA, Per Capita NNI, growth rates |
| 1 (Primary) | Census of India (censusindia.gov.in) | Population, literacy rate, urban-rural split |
| 1 (Primary) | RBI Handbook of Statistics (rbi.org.in) | Historical national accounts, inflation, monetary data |
| 2 (International) | World Bank Open Data (data.worldbank.org) | USD-denominated GDP, per capita USD, global comparisons |
| 2 (International) | UN World Population Prospects | Population estimates between Census years, projections |
| 3 (Survey-based) | ASER Reports (asercentre.org) | Literacy & learning outcomes between Census years |
| 3 (Survey-based) | NFHS / NSS / PLFS | Health, employment, household indicators |
2. GDP Methodology & Base Years
What GDP Measures
India’s GDP is the total value of all final goods and services produced within India’s borders in a financial year (April–March). MoSPI publishes GDP using the expenditure approach (PFCE + GFCE + GFCF + Change in Stocks + Exports − Imports) and the production/income approach (GVA at basic prices + Net taxes).
Base Years
| Series | Base Year | Coverage | Status |
|---|---|---|---|
| Old Series | 2004-05 | 1950-51 to ~2012 | Discontinued |
| 2011-12 Series | 2011-12 | 2011-12 to 2024-25 | Primary (back-series to 1950-51 available) |
| 2022-23 Series | 2022-23 | 2022-23 onwards | New series — released Feb 2026; back-series expected Dec 2026 |
Revision Cycle
MoSPI publishes GDP estimates in this sequence for each financial year:
- First Advance Estimate (FAE) — January, early in FY
- Second Advance Estimate (SAE) — February/March
- Provisional Estimate (PE) — May/June after year-end
- First Revised Estimate (FRE) — Following year January
- Second Revised Estimate (SRE) — Following year February
We always use the most recent available estimate and label it clearly (e.g., “PE 2024-25” or “FRE 2023-24”).
3. Population Methodology
India’s official population data comes from the decennial Census of India, conducted every 10 years. The last completed Census was in 2011. The 2021 Census was postponed due to COVID-19 and had not been released as of June 2026.
For inter-Census years, we use UN World Population Prospects 2024 estimates as the internationally recognised standard. These are not government of India figures and are shown with the UN label.
4. Literacy Rate Methodology
The official literacy rate is published by the Census of India. A person aged 7 and above who can read and write in any language is considered literate (Census definition). The most recent official Census literacy rate is 74.04% (Census 2011).
5. Per Capita Income Methodology
India’s official per capita income is the Per Capita Net National Income (NNI) published by MoSPI. NNI = GDP minus depreciation of capital (Consumption of Fixed Capital, or CFC). Per Capita NNI = NNI ÷ mid-year population estimate.
We show Per Capita NNI at both current prices (nominal, affected by inflation) and constant prices (real, adjusted to a base year). USD per capita figures use the World Bank’s Atlas method exchange rate.
6. How We Label Estimates vs Verified Data
| Label Used | What It Means |
|---|---|
| No label | Final, revised official government figure — not subject to further revision |
| PE (Provisional Estimate) | MoSPI’s first full-year estimate — may be revised once or twice more |
| FRE (First Revised Estimate) | First revision to the PE — more data available, more accurate |
| AE (Advance Estimate) | Early-year estimate — furthest from final, most likely to be revised |
| Estimate / Projected | Not from an official Census or primary survey — e.g. UN population projections |
| Survey-based | From ASER, NFHS, NSS etc. — not a Census figure; uses its own methodology |
7. Known Limitations
- No 2021 Census — post-2011 population and derived figures (literacy, per capita income denominator) are estimates
- GDP base year transition — figures before and after 2011-12 base year change are not directly comparable without adjustment
- USD figures vary with exchange rates — nominal USD GDP fluctuates with the rupee even if real growth is unchanged
- State-level data may lag — GSDP data for states is typically 1-2 years behind national GDP data
- Informal economy — GDP figures do not fully capture India’s large informal sector; informal estimates are research-based, not official
8. Update Policy
Each page on this platform shows a “Last verified” date that refers to the date on which we last checked and confirmed the figure against the original government source. This date is tied to the data itself — it is never automatically updated to “today’s date.” When MoSPI, RBI, or Census of India publishes new or revised figures, we update the relevant pages and change the Last verified date accordingly.