Questions: Lifecycle Hypothesis and Consumption-Saving Patterns

Question 1

A government sends every household a one-time tax rebate of $3,000. According to the lifecycle hypothesis, how should a household change its annual consumption?

• A. Increase consumption by roughly $3,000 in the current year
• B. Increase consumption by a small amount — spread the $3,000 over the remaining years of life
• C. Leave consumption unchanged — one-time windfalls are ignored by forward-looking consumers
• D. Increase consumption by $3,000 divided by the interest rate

Answer: (B)

The lifecycle hypothesis predicts that households smooth consumption across their remaining lifetime. A $3,000 one-time payment spread over, say, 30 remaining years raises optimal annual consumption by only $100 — a very low marginal propensity to consume (MPC) out of transitory income. Option A reflects the naive 'spend what you earn' view that LCH rejects. Option C goes too far — the windfall does raise lifetime wealth and therefore consumption, just by a small amount per period.

Question 2

Country A has 40% of its population retired and 60% working. Country B has 20% retired and 80% working. Assuming the lifecycle hypothesis holds, which country has the higher aggregate savings rate?

• A. Country A, because retirees are experienced savers who accumulated more wealth
• B. Country B, because its larger working-age population is in the saving phase of the lifecycle
• C. They are equal — lifecycle savings and dissavings cancel regardless of age distribution
• D. Country A, because retirees have more time to manage investments

Answer: (B)

The LCH's most powerful macroeconomic prediction: demographic structure determines aggregate saving. Workers are saving; retirees are dissaving. Country B's larger working cohort means more people in the saving phase and fewer drawing down wealth, producing a higher aggregate saving rate. Country A's older population is running down its wealth. This explains Japan's declining saving rate as its population aged, and China's historically high saving rate during its working-age-heavy demographic window.

Question 3

The lifecycle hypothesis predicts that individuals should accumulate wealth during working years and deplete it in retirement.

• T. True
• F. False

Answer: True

This is the core empirical prediction of the LCH. The optimal consumption-smoothing strategy requires borrowing (or saving little) when young and income is low, saving aggressively during peak earning years, and drawing down accumulated wealth in retirement when labor income falls to zero. The result is a hump-shaped wealth profile: rising through working years, peaking near retirement, then declining. This prediction is broadly supported by household wealth data across countries.

Question 4

The lifecycle hypothesis predicts that a person's consumption should closely follow their income year by year, rising when income rises and falling when income falls.

• T. True
• F. False

Answer: False

This is exactly what the lifecycle hypothesis argues against. Consumption should be smoothed across the whole lifetime, not tied to current income. If consumption tracked income, it would be low when young, high in middle age, and near zero in retirement — a highly volatile pattern. Instead, the LCH says people should borrow against future income when young, save when income is high, and dissave in retirement, keeping consumption roughly constant over the lifecycle. Excess sensitivity of consumption to current income is a violation of the LCH, not a prediction.

Question 5

Why does the lifecycle hypothesis predict that a permanent income increase raises consumption much more than an equal-sized temporary income increase?

Model answer: A permanent raise increases income in every future period, so lifetime wealth rises by roughly the full amount of the raise times the number of remaining periods. The optimal consumption increase is proportionally large. A temporary bonus adds to lifetime wealth only by the bonus amount, which is then spread over all remaining periods — so annual consumption rises by only 1/(remaining years) of the bonus. The marginal propensity to consume out of transitory income is therefore near zero, while MPC out of permanent income is near one.

This distinction has major implications for fiscal policy. Tax rebates (transitory) should produce small consumption responses; permanent tax cuts should produce large ones. Empirical evidence from the 2001 U.S. tax rebate and similar episodes broadly confirms that transitory payments have smaller consumption multipliers than permanent changes — consistent with the lifecycle framework and inconsistent with models where consumers simply spend current income.