Share of PISA 2009 sample in each social class group, for U.S., three top-scoring countries, and three similar post-industrial countries
| Social class group | Average distribution for three top-scoring countries | Average distribution for three similar post-industrial countries | Distribution, U.S. |
|---|---|---|---|
| Group 1 (Lowest) | 7% | 14% | 20% |
| Group 2 | 11 | 15 | 18 |
| Group 3 | 32 | 30 | 28 |
| Group 4 | 22 | 18 | 16 |
| Group 5 | 20 | 15 | 12 |
| Group 6 (Highest) | 8 | 8 | 6 |
Source: Authors' analysis of OECD Program for International Student Assessment (PISA) 2009 database for each country