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| stratified sampling; stratified random sampling; pre-stratification | |||
| stratified sampling method | |||
| 分层抽样法: 17 phrases in 7 subjects |
| Business | 2 |
| Commerce | 4 |
| Earth sciences | 1 |
| Ecology | 1 |
| Marketing | 4 |
| Quality control and standards | 1 |
| Technology | 4 |
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