Chapter 7 — Productivity, Technology, and Economic Growth
Chapter 7 — Productivity, Technology, and Economic Growth
Core question
Why can an economy produce more valuable output per person over decades, and who receives the gain?
Learning outcomes
You will be able to:
- distinguish total, per-person, and per-hour growth;
- explain capital deepening and diminishing returns;
- use technology and institutions as mechanisms rather than labels;
- interpret productivity evidence without generalising beyond its design.
1. Compound growth
For living standards, begin with real output or income per person—not total nominal GDP.
The Rule of 70 gives an approximate doubling time:
where g is annual percentage growth.
At 2%, doubling takes about 35 years; at 4%, about 17.5. Small persistent differences compound into large gaps.
2. Productivity is output per input
Common measures include output per worker, output per hour, and total factor productivity.
A compact production function is:
where:
K: physical and intangible capital;H: skills, knowledge, and health;L: labour input;A: efficiency with which inputs are combined.
The equation organises explanations. It does not tell us automatically how to measure A or prove causation.
3. Capital deepening and diminishing returns
Giving a worker a first useful machine may raise output greatly. A tenth identical machine with no extra labour, power, space, or demand may add little.
With other inputs fixed:
Capital accumulation can support convergence when poorer economies adopt proven technologies and basic infrastructure. It does not guarantee convergence: governance, complementary skills, finance, conflict, geography, and market access affect returns.
4. Ideas and organisation
Technology includes:
- a new product or production process;
- a management practice that reduces errors;
- logistics, standards, and interoperability;
- scientific knowledge and software;
- a new organisational form.
Ideas are partly non-rival: one person's use need not prevent another's. But diffusion can be limited by intellectual property, tacit knowledge, skills, data, compatibility, and market power.
5. Evidence case: generative AI at work
Brynjolfsson, Li, and Raymond studied staggered deployment of a generative-AI assistant to 5,172 customer-support agents. Access increased issues resolved per hour by about 15% on average, with larger gains for less-experienced and lower-skill workers; effects were small for the most experienced group, with some quality concerns at the top (QJE, 2025).
Correct inference:
In this firm and task, the tool raised measured productivity on average and compressed some experience gaps.
Incorrect inference:
AI raises every worker's productivity by 15%.
The study illustrates both technology-driven productivity and heterogeneous incidence. Economy-wide effects also depend on adoption cost, task redesign, prices, entry, labour reallocation, new demand, and who owns complementary assets.
6. Institutions shape return and diffusion
Institutions influence whether people expect effort, investment, entry, and innovation to be rewarded.
Relevant mechanisms include:
- predictable contracts and property rights;
- effective public administration and infrastructure;
- competition and the ability of productive firms to enter and expand;
- finance for worthwhile investment;
- education and health that build capability;
- political accountability and protection from extraction.
“Institutions matter” is incomplete. Identify which rule changes which incentive, for whom, and with what evidence.
7. Growth, distribution, and sustainability
Average productivity growth can coexist with:
- wage stagnation for some groups;
- regional decline and job displacement;
- rising returns to capital or scarce skills;
- longer or shorter working hours;
- natural-capital depletion and emissions.
A growth assessment should report:
output per person + output per hour + median real income
+ distribution + labour transition + natural/produced asset change
Growth expands feasible choices; institutions and policy shape how gains, costs, and risks are distributed.
8. Evaluate a growth policy
| Policy | Intended mechanism | Complement needed | Risk |
|---|---|---|---|
| infrastructure | lower transport/coordination cost | maintenance and useful location | low-return project |
| education | raise skills and adaptability | teaching quality and labour demand | credentials without learning |
| R&D support | knowledge spillovers | competition and diffusion | capture by incumbents |
| entry reform | reallocate toward productive firms | finance and worker transition | unstable low-quality entry |
| health investment | more effective labour and well-being | delivery capacity | unequal access |
List mechanisms and failure conditions, not slogans.
Practice: growth decomposition
Country A's output grows 4%, labour hours 1%, and population 2%.
- Approximate output-per-hour growth.
- Approximate output-per-person growth.
- Give one capital, skill, and technology explanation.
- Name evidence needed to distinguish them.
- Explain why the average does not establish distributional gain.
Answer check
Quick check
- Growth in total output and output per person are different.
- Capital deepening faces diminishing returns without complements.
- Technology includes organisation and diffusion, not only invention.
- Productivity effects can vary sharply across workers and tasks.
- Sustainable growth requires distribution and asset stocks to be examined.
Next: study the monetary and banking system that finances activity and transmits risk.
Chapter 6 — Inflation, Purchasing Power, and Labour Markets
Price indices, real values, inflation mechanisms, employment definitions, participation, vacancies, and short-run trade-offs.
Chapter 8 — Money, Credit, and Banking
Money, deposits, bank balance sheets, credit creation, capital, liquidity, duration risk, bank runs, and central banks.