Inflation: measurement (CPI/WPI), causes & control

What inflation is, and how India measures it

Inflation is a sustained rise in the general price level, eroding the purchasing power of money. India measures it through two principal index families.

Consumer Price Index (CPI): Compiled by the National Statistical Office (NSO) under the Ministry of Statistics and Programme Implementation (MoSPI), the CPI (Combined) has a base year of 2012 and is the headline retail inflation gauge. It is the price of a fixed consumption basket faced by households. Food and beverages carry roughly 45.86% weight, with food & beverages plus fuel forming the volatile component. The current CPI series merged the older CPI-Industrial Workers (CPI-IW, base 2016, compiled by the Labour Bureau), CPI-Agricultural Labourers (CPI-AL) and CPI-Rural Labourers. Since the 2016 amendment to the RBI Act, 1934 (Section 45ZA), CPI (Combined) is the official target variable for monetary policy.

Wholesale Price Index (WPI): Compiled by the Office of the Economic Adviser, Department for Promotion of Industry and Internal Trade (DPIIT), base year 2011-12, the WPI captures prices at the wholesale/producer stage. It has three groups: Primary Articles (~22.6%), Fuel & Power (~13.2%), and Manufactured Products (~64.2%). Crucially, WPI excludes services entirely, whereas CPI includes them. WPI is not the policy target but signals input-cost pressure.

Why the two indices diverge

The CPI and WPI frequently move in opposite directions. WPI is dominated by manufactured goods and global commodity prices (crude, metals); CPI is dominated by food and services. In 2020-21, WPI briefly turned negative on collapsing oil prices while CPI stayed elevated on food. The gap matters because a candidate must explain which inflation the RBI targets and why food shocks (a supply phenomenon) drive headline CPI even when core (CPI excluding food and fuel) is stable.

Allied measures you must know

• GDP deflator: the ratio of nominal to real GDP, the broadest price measure, covering all domestically produced goods and services.
• Core inflation: CPI excluding food and fuel; the RBI watches it for demand-side, persistent pressure.
• Headline inflation: the full CPI basket including volatile food and fuel.
• Housing index in CPI uses house rent; it is absent in WPI.

Key distinctions UPSC tests: deflation (falling general prices), disinflation (a falling rate of inflation), stagflation (high inflation with stagnant growth and high unemployment, as in the 1970s oil shocks), and skewflation (a price rise in some sectors, typically food, while others are stable) — the last term was popularised in the Economic Survey 2010-11.

Causes of inflation

Demand-pull inflation arises when aggregate demand outstrips supply — fuelled by excess money supply, deficit financing, rising incomes, or loose credit. Milton Friedman's dictum that "inflation is always and everywhere a monetary phenomenon" captures the monetarist view that excessive money growth is the root cause.

Cost-push inflation arises from rising input costs: higher wages, costlier imported crude (the 1973 and 1979 OPEC shocks), supply-chain disruptions (as during COVID-19, 2020-22), or higher administered prices and indirect taxes. Imported inflation is a sub-type — a depreciating rupee raises the rupee cost of imports.

Structural/bottleneck inflation, emphasised by Indian economists, reflects agricultural supply rigidities, inadequate infrastructure, and hoarding. Food inflation in India is frequently structural — driven by monsoon failure, low productivity in pulses and vegetables, and the cobweb in perishables.

Controlling inflation: the toolkit

Monetary policy (RBI): Under the flexible inflation-targeting (FIT) framework introduced by the Finance Act 2016 and the RBI Act amendment, the Monetary Policy Committee (MPC) — six members, the Governor casting the deciding vote — is mandated to keep CPI inflation at 4% with a tolerance band of +/- 2% (i.e., 2-6%). This target, set by the Centre in consultation with the RBI, was first notified for 2016-2021 and renewed for 2021-2026 (notified March 31, 2021). To curb inflation the RBI raises the repo rate, conducts open market operations to absorb liquidity, and may raise the CRR/SLR. A failure — inflation outside the band for three consecutive quarters — obliges the RBI to write to the Government explaining causes and remedies, as it did in November 2022 after CPI breached 6% for nine straight months.

Fiscal policy (Government): Reducing the fiscal deficit, cutting indirect taxes (e.g., excise duty cuts on petrol/diesel in May 2022), and curbing wasteful expenditure dampen demand-pull pressure.

Administrative/supply-side measures: Releasing buffer stocks via the Food Corporation of India, imposing stock limits under the Essential Commodities Act, 1955, banning or taxing exports (wheat export ban, May 2022; rice export curbs, 2023), cutting import duties on edible oils and pulses, and running the Price Stabilisation Fund for onions and pulses.

High-yield retention points

• CPI base 2012; WPI base 2011-12. CPI includes services, WPI does not.
• Target: 4% +/-2% CPI; failure clause = 3 consecutive quarters outside band.
• MPC = 6 members; Governor has the casting vote.
• The 1991 crisis and the 2008 spike were periods of double-digit inflation; the 2013 "taper tantrum" combined inflation with rupee depreciation.

Is inflation targeting right for India?

The FIT framework, recommended by the Urjit Patel Committee (2014), replaced the RBI's earlier 'multiple indicator approach'. Critics argue that targeting headline CPI — which is ~46% food — forces the RBI to respond with interest rates to supply shocks (a failed monsoon) over which monetary policy has no traction; raising the repo rate cannot grow more onions. Proponents counter that anchoring inflation expectations is itself valuable, and that food shocks, if persistent, leak into core inflation and wages.

The 2021-2026 review retained the 4% +/-2% target after debate over whether to shift to core CPI or widen the band; the Government chose continuity, citing the framework's success in lowering average inflation from the 9-10% of 2011-13 to within band for most of 2016-2019.

The trade-offs a Mains answer must capture

• Phillips curve: the short-run inverse relation between inflation and unemployment — controlling inflation can cost growth and jobs.
• Misery index: inflation plus unemployment; a shorthand for welfare loss.
• Inflation tax: inflation erodes the real value of money holdings, an implicit tax that hurts the poor most, since they hold more cash and cannot hedge.
• Distributional effects: debtors gain, creditors and fixed-income earners (pensioners) lose; this underpins the equity case for price stability.

The fiscal-monetary coordination angle

The abolition of ad hoc Treasury Bills (1997) and the FRBM Act, 2003 ended automatic monetisation of deficits, separating the printing press from the budget. Excessive deficit financing remains a structural inflation risk, which is why GS-3 answers should always link fiscal discipline to price stability. A strong answer integrates RBI tools, Government supply-side action, and the structural reform of agricultural markets — not monetary policy alone.