ECON30005 · Money and Banking
Monetary Transmission, Expectations and Inflation Targeting
Week 8 explains how policy-rate changes reach output and inflation through the interest-rate, asset-price, exchange-rate and credit channels, with expectations of future real rates at the centre. It develops the New Keynesian model (the dynamic IS curve and the forward-looking Phillips curve), inflation targeting and the need for a nominal anchor, the time-inconsistency problem, and why central banks target small positive inflation rather than zero. Expect true/false on commitment and supply shocks, short essays on transmission, and an NK Phillips-curve calculation.
What this chapter covers
- 01Transmission channels: the traditional interest-rate channel (r ↓ ⇒ investment ↑ ⇒ demand ↑), plus asset-price, exchange-rate and credit channels
- 02The central role of expected future real rates and the Fisher relation r = i − π with sticky prices
- 03The New Keynesian dynamic IS curve: the output gap depends on the expected future gap and the real-rate/natural-rate gap
- 04The NK Phillips curve π_t = β·E_t(π_{t+1}) + κ·ŷ_t — forward-looking, unlike the static Phillips curve
- 05Why expectations amplify credible policy, and why a promise of low future rates can stimulate today (even at the zero lower bound)
- 06Inflation targeting: a public numerical target, commitment, transparency and accountability as a nominal anchor
- 07The time-inconsistency problem and why a nominal anchor is a commitment device
- 08Why target small positive inflation, not zero: zero-lower-bound room, deflation risk and downward nominal wage rigidity
The New Keynesian Phillips curve and the power of expectations
- +1Write the curve: current inflation π_t equals β times expected future inflation plus κ times the current output gap. Inflation is driven mostly by what firms expect future inflation to be, plus a smaller push from current activity.
- +1(a) Anchored expectations: π_t = 0.99·(2) + 0.3·(1) = 1.98 + 0.3 = 2.28%. With expectations near target, inflation stays close to target despite the positive output gap.
- +1(b) De-anchored expectations: π_t = 0.99·(4) + 0.3·(1) = 3.96 + 0.3 = 4.26%. Holding the output gap fixed, the 2-point rise in expected inflation raises current inflation by about 1.98 points — almost one-for-one.
- +1Lesson: expected future inflation dominates the current output gap in setting inflation today. That is why a credible nominal anchor (inflation targeting) is so powerful — anchoring E_t(π_{t+1}) does most of the work, and a credible promise about future policy can move inflation now, even before output responds and even at the zero lower bound.
Key terms
- Monetary transmission mechanism
- The set of channels — interest-rate, asset-price, exchange-rate and credit — through which a change in the policy rate reaches investment, consumption, output and inflation, working largely through expected future real interest rates.
- New Keynesian IS curve
- The dynamic IS relation ŷ_t = E_t(ŷ_{t+1}) − (1/σ)[i_t − E_t(π_{t+1}) − r_t^n]: today's output gap depends on the expected future gap and on the gap between the real rate and the natural rate.
- New Keynesian Phillips curve
- π_t = β·E_t(π_{t+1}) + κ·ŷ_t: inflation today depends on expected future inflation and the current output gap. The forward-looking expectations term distinguishes it from the static Phillips curve.
- Nominal anchor
- A publicly stated commitment (such as an inflation target) that pins down expectations of the value of money. Under fiat money nothing else pins prices down, so the anchor is essential and acts as a commitment device.
- Time-inconsistency problem
- The temptation for a policymaker to deviate from a previously optimal plan — for example to engineer a short-run output boost — which rational agents anticipate, raising inflation without lasting output gains. A nominal anchor addresses it.
- Inflation targeting
- A monetary framework built on a public medium-term numerical inflation target, institutional commitment to price stability, transparency and accountability. Small positive targets (not zero) leave room above the zero lower bound and guard against deflation.
Monetary Transmission, Expectations and Inflation Targeting FAQ
Why do expectations matter so much in the New Keynesian model?
Because both key equations are forward-looking. In the Phillips curve, firms that can reset their price only occasionally set it based on expected future inflation, so with β near one a change in expected inflation passes almost one-for-one into current inflation. In the IS curve, forward-looking households base spending on the whole expected path of real rates. Iterating the equations makes today's output and inflation depend on the entire expected future, which is why credibility and commitment are decisive.
Why do central banks target small positive inflation rather than zero?
Three reasons. First, a positive target keeps nominal rates above zero in normal times, leaving room to cut before hitting the zero lower bound. Second, it provides a buffer against deflation, which can set off debt-deflation dynamics. Third, with downward nominal wage rigidity, mild inflation lets real wages adjust without nominal wage cuts — it 'greases the wheels'. Zero inflation would forgo all three, so targets like 2% or the RBA's 2-3% are standard.
How can a promise about future policy stimulate the economy today?
Because spending and price-setting depend on expected future real rates. If the central bank credibly commits to keeping rates low (or letting inflation run a little higher) in the future, expected future real rates fall and expected inflation rises, which lowers today's expected real rate and lifts current demand — even if the current policy rate is stuck at the zero lower bound. This is the forward-guidance logic, and a related true/false ('a credible commitment to low future rates stimulates current activity') is true.
Can AI help me with transmission and inflation targeting in ECON30005?
Yes. Sia can compute the NK Phillips curve on fresh numbers, trace the transmission channels step by step, and explain time-inconsistency and the nominal-anchor argument. Use it to rehearse the model and the intuition; it does not sit graded assessment for you, and you should confirm the rules on Canvas.
Exam move
Organise the week around expectations. Be able to write and interpret the two New Keynesian equations — the dynamic IS curve and the forward-looking Phillips curve π_t = β·E_t(π_{t+1}) + κ·ŷ_t — and to compute the Phillips curve on fresh numbers, noting that β ≈ 1 makes expected inflation nearly a one-for-one driver. For essays, rehearse the transmission channels (interest-rate, asset-price, exchange-rate, credit) as labelled chains, and the inflation-targeting case: a nominal anchor solves time-inconsistency, and small positive inflation beats zero. Memorise two subtle true/false answers: a credible commitment to low future rates stimulates today (true), and a central bank should fully ignore temporary supply shocks (false — they can un-anchor expectations). This is a conceptually dense week, so a one-page map of channels and equations pays off. Confirm the exam structure on Canvas.
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