Inflation and its impact on the economy and supply chains

By Damon Frith, Wealth Editor, NAB Private Wealth

Inflation is one of the most closely watched indicators in modern economics, as it shapes everything from household purchasing power to business investment decisions and central‑bank policy.  

Some inflation is healthy for an economy, as it encourages spending and investment and supports wage and job growth.

At its core, inflation is the sustained increase in the general price level of goods and services over time. While modest inflation is a normal feature of a growing economy, elevated or volatile inflation can distort decision‑making, disrupt supply chains, and erode confidence across the economic system.

Headline inflation vs Trimmed‑mean inflation

Understanding inflation requires distinguishing between different measures. Two of the most important are headline inflation and trimmed‑mean inflation.

Headline Inflation

Headline inflation measures the total change in the consumer price index (CPI), including all categories such as food, fuel, housing, and transport. It captures the full impact of inflation on consumers but is highly sensitive to volatile items-especially energy and fresh food.

For example, a sudden spike in oil prices can cause a sharp increase in headline inflation, even if underlying demand conditions are stable.

Trimmed‑Mean Inflation

Trimmed‑mean inflation is a core inflation measure that removes the most extreme price movements,  typically the top and bottom 10-20% of price changes each month. The goal is to isolate the underlying trend in inflation by filtering out temporary shocks.

Central banks, including the Reserve Bank of Australia, rely heavily on trimmed‑mean inflation because it provides a more stable signal for policy decisions.

Why the Distinction Matters

• Headline inflation reflects the lived experience of households and is crucial for understanding cost‑of‑living pressures.
•  Trimmed‑mean inflation guides monetary policy because it indicates whether inflationary pressures are broad‑based or driven by temporary volatility.

When headline inflation is high but trimmed‑mean inflation is moderate, policymakers may view the shock as temporary. When both are elevated, inflation is more likely to be persistent and systemic.

Why Inflation Occurs

Inflation typically emerges from three broad forces:

• Demand‑pull inflation - when total demand outpaces the economy’s capacity to supply goods and services.
• Cost‑push inflation - when production costs rise (energy, wages, raw materials), forcing businesses to increase prices.
• Built‑in inflation - when expectations of future inflation become embedded in wage negotiations and pricing behaviour. Often referred to as ‘sticky inflation’.

Inflation is usually the result of multiple forces interacting simultaneously. For example, the post‑pandemic period saw strong demand, supply bottlenecks, and energy price shocks all reinforcing each other.

Economic Impacts of Inflation

Inflation affects the economy through several channels, and the impacts may be disproportional to modelled outcomes.

1. Purchasing Power and Household Behaviour

As prices rise, real incomes fall unless wages keep pace. This reduces discretionary spending and shifts consumption patterns toward essentials. Households may delay major purchases, increase savings buffers or shift to lower‑cost substitutes. These behavioural adjustments can slow economic growth.

2. Business Investment and Profitability

Inflation complicates business planning. Firms face:

• Higher input costs, especially for energy, transport, and materials.
• Uncertainty about future prices, making long‑term investment riskier.
• Potential margin compression if they cannot pass on costs to consumers.

In high‑inflation environments, businesses often shorten planning cycles, hold less inventory, and seek higher risk premiums for capital investment.

3. Interest Rates and Financial Markets

Central banks respond to inflation by tightening monetary policy. Higher interest rates:

• Increase borrowing costs for households and firms.
• Reprice asset valuations, particularly long‑duration assets.
• Strengthen the currency, affecting export competitiveness.

Financial markets become more volatile because inflation introduces uncertainty into earnings forecasts, liquidity conditions and discount rates (As interest rates rise, the discount rate applied to future earnings increases, reducing the present value of stocks, bonds, and other financial assets).

Inflation’s Impact on Supply Chains

Supply chains are both a cause and victim of inflation. Modern supply networks are globally integrated, time‑sensitive, and heavily dependent on energy and logistics. Inflation disrupts these systems in several ways.

1. Rising Input and Transportation Costs

Energy prices, particularly oil and gas, feed directly into freight, manufacturing, and distribution. When fuel costs spike, logistics providers raise prices, which cascade through the supply chain. This is a classic cost‑push dynamic.

2. Inventory Management Challenges

Inflation increases the cost of holding inventory. Businesses may reduce stock levels to manage working capital, but this increases vulnerability to shortages. In times of external events, such as an oil supply shock, some businesses may seek to build inventory, which can amplify supply‑demand imbalances.

3. Supplier Instability

Small and mid‑sized suppliers often struggle with cash‑flow pressures during inflationary periods. If they cannot secure financing or pass on costs, they may reduce output or exit the market, creating bottlenecks for downstream producers.

Conclusion

Inflation is not simply a rise in prices; it is a complex, system‑wide phenomenon that reshapes economic behaviour, supply‑chain dynamics, and policy decisions. As economies become more interconnected and supply chains more fragile, managing inflation requires a nuanced understanding of both macroeconomic forces and the micro‑level realities of production and logistics.

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