double sampling for stratification

例句：

1. 1.The company's strategy for growth isto expand into new markets.
   公司的发展战略是拓展到新的市场。
2. 2. The team decided tostratify their resources based on theproject's complexity.
   团队决定根据项目的复杂程度来分配资源。
3. 3. Theresearch group conducted astratified sampling of the populationto ensure representativeness.
   研究小组对人群进行了分层抽样，以确保代表性。