New Business Herald

Tag: Inflation

  • CPI, Core and PPI: How to Read Inflation Data Without Being Misled

    Inflation is reported as a single number, which is the source of most misunderstanding about it. There is no single inflation rate. There are several indices, built on different baskets, using different methods, updated on different schedules, and they routinely tell different stories about the same month. Knowing which one you are looking at — and what it structurally cannot capture — is most of the skill in reading the data.

    The Consumer Price Index

    CPI is the headline measure in most countries. It tracks the price of a fixed basket of goods and services intended to represent what a typical urban household buys, with each item weighted by its share of spending.

    Two features of that construction matter enormously.

    First, the basket is fixed between revisions. If beef becomes expensive and households switch to chicken, CPI continues to price beef at its old weight for a period. This is the substitution bias, and it tends to overstate the true cost-of-living increase people experience.

    Second, weights determine everything. Housing is the largest single component in most CPI baskets. A modest change in the shelter figure moves headline CPI more than a dramatic swing in a small category. When commentators say inflation was “driven by” some component, they usually mean it had a large weight, not that its price moved most.

    Why shelter lags reality

    Housing deserves separate treatment because it is where CPI most visibly diverges from lived experience.

    Statistical agencies do not measure house prices in CPI — a house is an asset, and CPI measures consumption. Instead they measure the cost of shelter services: rents actually paid by tenants, plus an imputed figure for owner-occupiers, usually called owners’ equivalent rent, estimating what the owner would pay to rent the same property.

    The sample includes all existing leases, not just newly signed ones. Since most tenancies run twelve months or longer, the index reflects rents agreed across the previous year. When market rents turn, the CPI shelter component follows with a lag typically measured in several quarters. Analysts watch new-lease rent indices to anticipate where official shelter inflation will be well before it appears.

    Core inflation, and why it is not a trick

    Core inflation is the headline index with food and energy removed. This reliably provokes the objection that food and energy are precisely what people buy — which is true, and beside the point.

    Core is not an attempt to describe household experience. It is an attempt to extract signal. Food and energy prices are set substantially by weather, harvests, geopolitics and supply shocks — forces that are volatile, frequently reverse, and are entirely unresponsive to interest rates. A central bank raising rates cannot alter the price of oil.

    Stripping them out gives a cleaner read on the underlying, demand-driven trend that policy can influence. Headline inflation tells you what happened to household budgets. Core inflation tells you what is likely to persist. Both are useful; they answer different questions.

    Analysts increasingly supplement core with narrower cuts — services excluding housing, trimmed-mean and median measures that discard outliers at both ends — all attempting the same thing: separating persistent inflation from noise.

    The Producer Price Index

    PPI measures prices received by domestic producers for their output, rather than prices paid by consumers. It sits earlier in the supply chain, which is why it is often treated as a leading indicator.

    Treat that reading with care. The pass-through from producer to consumer prices is real but incomplete and slow. Firms absorb cost increases in margin when competition prevents them raising prices, and expand margin when input costs fall without cutting prices. PPI also covers a different universe — it includes goods sold to other businesses and excludes imports, which form a substantial share of consumer spending.

    A PPI spike signals cost pressure building. It does not reliably predict the size or timing of any consumer price response.

    PCE and why central banks may prefer it

    In the United States, the Federal Reserve’s stated target is the Personal Consumption Expenditures price index rather than CPI. The two differ in three structural ways.

    • Scope. PCE captures spending made on households’ behalf — notably employer- and government-funded healthcare — which CPI largely excludes. This gives healthcare a much larger PCE weight.
    • Weights. PCE updates its weights continuously rather than periodically, so it adapts to substitution as it happens.
    • Formula. The two use different aggregation methods, which produces a persistent gap.

    PCE typically runs somewhat below CPI as a result. Comparing a PCE target to a CPI print is a common and consequential error.

    Base effects: the trap in year-over-year figures

    Annual inflation compares today’s index to the same month a year ago. That means it is determined by two numbers, and the older one is fixed history.

    If prices spiked twelve months ago, the annual rate will fall this month even if prices are currently rising briskly — the comparison base is simply high. This is a base effect. It is arithmetic, not disinflation.

    The defence is to look at month-over-month changes, usually annualised, and at three- and six-month annualised rates. These reveal the current run-rate. When monthly momentum diverges sharply from the annual figure, the monthly series is describing the present and the annual figure is describing last year.

    Seasonal adjustment and revisions

    Most reported series are seasonally adjusted to strip predictable calendar patterns — holiday retail, summer fuel demand, new-year price resets. Comparing a seasonally adjusted figure to an unadjusted one produces nonsense.

    Seasonal factors are themselves estimated from history and get revised. A month that looked alarming on release can look ordinary after revision. Any single print carries meaningful uncertainty; the trend across several months carries far more information than the latest number.

    A practical reading order

    • Identify the index and whether it is headline or core, adjusted or unadjusted.
    • Read the month-over-month change before the annual rate.
    • Check three- and six-month annualised rates for the current run-rate.
    • Ask whether the annual move is a base effect.
    • Decompose by contribution — weight times price change — not by which price rose most.
    • Treat shelter as a lagging signal and read new-lease data for the leading one.
    • Wait for confirmation across months before concluding a trend has turned.

    None of this requires specialist tools. The statistical agencies publish the component detail alongside the headline, and the discipline of reading it is what separates a useful interpretation from a misleading one.

    Related reading

    For how central banks respond to these figures, see how central bank rate decisions reach the real economy.

    This article is general information and journalism, not investment advice. See our Editorial Policy.

  • How Central Bank Rate Decisions Reach the Real Economy

    When a central bank announces a change to its policy rate, the headline is instant. The economic effect is not. The rate a central bank actually sets governs overnight lending between banks — a market most households and businesses never touch directly. Everything that follows is transmission: a sequence of adjustments through which a change in that overnight rate works its way into mortgage payments, business investment decisions, currency values and, eventually, prices.

    Understanding that sequence explains most of what is otherwise confusing about monetary policy — including why central banks keep tightening after inflation appears to be falling, and why the economy often seems unaffected for months before turning sharply.

    What the policy rate actually is

    A policy rate is the rate at which commercial banks lend reserves to one another overnight, steered by the central bank. In the United States this is the federal funds rate; the European Central Bank, the Bank of England and others operate equivalent instruments under different names.

    Modern central banks generally do not force this rate by rationing reserves. They set it administratively — principally by choosing what they pay banks on reserves held at the central bank. No bank will lend to another at meaningfully less than it can earn risk-free at the central bank, so that floor drags market rates with it. This matters because it means the policy rate moves immediately and reliably. Everything downstream is where the delay lives.

    Channel one: the interest rate channel

    The most direct route runs through the price of borrowing. The overnight rate anchors short-term money market rates, which anchor the benchmarks banks use to price loans. Floating-rate products — credit lines, many business loans, variable-rate mortgages — reprice quickly, sometimes within a single billing cycle.

    Longer-dated borrowing responds differently. A ten-year yield reflects not today’s overnight rate but the market’s average expectation of that rate over the next decade, plus a term premium for bearing duration risk. This is why a central bank can raise rates while long-term yields barely move, or even fall: if markets read the increase as evidence that policy will succeed in suppressing inflation, expectations of future rates can decline even as the current rate rises.

    Higher borrowing costs then suppress interest-sensitive spending. Housing responds first and hardest, because a mortgage payment is almost entirely a function of the rate. Business capital expenditure follows: projects whose expected return sat just above the old cost of capital fall below the new one and get shelved.

    Channel two: the credit channel

    Price is not the only thing that changes. Availability does too.

    Higher rates weaken borrower balance sheets — debt service costs rise, collateral values soften — which makes lenders more cautious at any given interest rate. Banks tighten lending standards: larger deposits, stricter covenants, lower loan-to-value limits, outright refusal for marginal borrowers. A small business may find not that credit is expensive but that it is unavailable.

    This channel falls unevenly. Large firms with access to bond markets and cash reserves are relatively insulated. Small and mid-sized firms dependent on bank relationships absorb a disproportionate share of the tightening — one reason monetary policy tends to bite hardest on exactly the businesses least equipped to withstand it.

    Channel three: asset prices and wealth

    Asset valuation is discounting: an asset is worth the present value of the cash it will generate. Raise the discount rate and present value falls, mechanically, before any change in the underlying cash flows.

    The effect is largest for assets whose cash flows sit furthest in the future — long-duration growth equities, speculative ventures, long-dated bonds. Households that feel poorer because their portfolios and property have fallen in value tend to spend less, which feeds back into demand.

    Channel four: the exchange rate

    When a country’s rates rise relative to its trading partners’, its assets become more attractive to foreign capital. Demand for the currency increases and it appreciates.

    A stronger currency lowers the domestic price of imports, which directly reduces measured inflation, while making exports less competitive abroad. For small open economies this channel can be more powerful than the domestic interest rate channel. For large, relatively closed economies it is a secondary effect.

    Channel five: expectations

    The subtlest channel is also the one central bankers talk about most. Inflation depends partly on what people expect inflation to be. Wage negotiations, supplier contracts and pricing decisions all embed an assumption about future price levels — and those assumptions become self-fulfilling.

    A central bank that is believed can therefore influence behaviour through announcement alone. A central bank that is not believed must actually crush demand to achieve the same result. This is why credibility is treated as an asset worth protecting at considerable short-term cost, and why officials continue to sound hawkish well after the data has turned.

    Why the lags are long and variable

    Each channel operates on its own timetable. Financial markets reprice in seconds. Bank lending standards shift over a quarter or two. Housing activity responds over several quarters. Business investment plans, often committed years in advance, unwind slower still. Employment adjusts late, because firms defer layoffs until they are confident demand has genuinely weakened. Wage and price setting, tied to annual cycles, is slower again.

    Aggregate those and the peak effect of a rate change on inflation typically arrives somewhere between one and two years later — Milton Friedman’s “long and variable lags.” The variability is as important as the length. The lag depends on how indebted households are, what proportion of mortgages are fixed versus floating, how healthy bank balance sheets are, and how credible the central bank is at that moment.

    What this means for reading policy decisions

    Three implications follow directly.

    • Current inflation is the wrong target. A central bank setting policy against today’s inflation print is steering by a rear-view mirror. It must act on where inflation is forecast to be once the lag has run.
    • Policy in place is still working. Rates held steady after a tightening cycle are not neutral; the effects of earlier increases continue to accumulate.
    • Over-tightening is discovered late. Because the damage appears well after the decision, the risk of going too far is intrinsic to the process rather than a sign of incompetence.

    The apparent puzzle — why a central bank keeps its foot on the brake while the economy looks fine — dissolves once the lag structure is visible. The question officials are answering is not whether conditions are tight today, but whether they will be tight enough eighteen months from now.

    Related reading

    For how the resulting inflation is measured, see our guide to reading inflation data. For how rate expectations show up in bond markets, see what an inverted yield curve actually signals.

    This article is general information and journalism, not investment advice. See our Editorial Policy.