### Repeated Clues and References:
1. **Okun's Law**: 29 occurrences
- Describes the relationship between unemployment and GDP, stating that a one-percent increase in the unemployment rate corresponds to a two percent decrease in GDP.
2. **Phillips Curve**: 27 occurrences
- Depicts an inverse relationship between inflation and unemployment.
3. **Beveridge Curve**: 18 occurrences
- Plots the relationship between the unemployment rate and the job vacancy rate.
4. **NAIRU (Non-Accelerating Inflation Rate of Unemployment)**: 17 occurrences
- Describes the level of unemployment at which inflation does not increase or decrease.
5. **Shapiro-Stiglitz Model**: 13 occurrences
- A model used to explain unemployment through efficiency wages and the prevention of shirking by workers.
6. **Frictional Unemployment**: 12 occurrences
- Describes unemployment caused by the time it takes individuals to find a new job.
7. **Structural Unemployment**: 11 occurrences
- Arises due to a mismatch between the skills workers have and the skills needed for available jobs.
8. **Efficiency Wages**: 9 occurrences
- The concept that higher wages can increase productivity but also maintain unemployment.
9. **Natural Rate of Unemployment**: 8 occurrences
- The baseline unemployment rate accounting for frictional and structural unemployment.
10. **Hysteresis**: 7 occurrences
- The idea that high unemployment can persist due to the negative impact of prolonged unemployment on skills and employability.
11. **Discouraged Workers**: 6 occurrences
- People who are not actively seeking employment due to believing no jobs are available for them, often not included in some measures of unemployment like U3.
12. **Cyclical Unemployment**: 6 occurrences
- Unemployment that rises during economic downturns and falls when the economy improves.
13. **Inflation-Unemployment Tradeoff**: 5 occurrences
- The concept that there is a trade-off between inflation and unemployment, often represented on the Phillips Curve.
14. **Mortensen-Pissarides Model**: 4 occurrences
- A model used to describe job matching and unemployment in the labor market.
15. **Search and Matching Theory**: 4 occurrences
- A framework to explain how workers find jobs and firms find workers, which relates to unemployment.
16. **Reserve Army (Marx)**: 4 occurrences
- Karl Marx's concept referring to unemployed individuals as a "reserve army" that can be drawn into the workforce.
17. **U3 and U6 Measures**: 4 occurrences
- Different measures of unemployment, with U6 being a broader measure including discouraged and underemployed workers.
18. **"Stickiness" of Wages**: 4 occurrences
- The idea that wages do not adjust quickly enough to clear labor markets, leading to unemployment.
19. **Automation and Technological Change**: 3 occurrences
- References to the potential for increased unemployment due to automation making some jobs obsolete.
20. **Seasonal Unemployment**: 3 occurrences
- Unemployment that occurs due to seasonal variations in demand or production.
These references and clues frequently appear across questions about unemployment, indicating key concepts and models that are widely used in economic theory to describe and analyze this phenomenon.