Life-Cycle Hypothesis Model

Evidence and data

Use age-income profiles, wealth, pension rules, retirement ages, survival risk, bequests, housing, and credit constraints.

Calibration or measurement

Planning horizon, retirement length, interest rates, initial wealth, bequest motives, and income risk determine the saving path.

Boundaries

• Uncertain lifespan and health costs alter the drawdown path.
• Housing and pensions are illiquid for many households.
• Aggregate saving may not mirror a representative household profile.

Use guidance

When sufficient

Retirement-saving arithmetic and pension-system design when the household faces a deterministic income path, a known retirement date, and a fixed planning horizon. Aggregate saving rates, demographic dividend calculations, and the direction of pay-as-you-go pension reforms are all well-handled by the lifecycle structure (Modigliani and Brumberg 1954; Ando and Modigliani 1963).

When sketch only

Do not use where bequest motives, mortality risk, or health costs alter the drawdown profile, which is most real-world retirement analysis. The hump-shaped saving profile is the core prediction; if the data show persistent saving in old age, the model requires a precautionary-saving or bequest extension before it can match the facts.

When to switch

Switch to a stochastic lifecycle model (Hubbard, Skinner, and Zeldes 1995 JPE) when medical-expenditure risk or income uncertainty in retirement is the question. Switch to an OLG model (theoretical:olg) when generational interactions, social security incidence, or capital accumulation across cohorts are at stake.

Falsification signal

The retirement-savings puzzle: wealth profiles in household survey data (HRS, PSID) decline far more slowly in retirement than the basic model predicts, implying either strong bequests motives, precautionary saving against medical costs, or both. A household panel that shows continued positive net saving after retirement in a broad cross-section falsifies the simple decumulation prediction.