Field-based Multistage Sampling

Imagine surveying agricultural households across a large country. You cannot list every household in advance. Instead you first randomly select provinces, then within each chosen province you randomly select districts, then within each district you send field teams to enumerate and randomly select villages, and finally within each village field teams select individual households. Each stage narrows the physical territory until fieldworkers can approach the final units directly. This nested, geographically grounded logic — random selection at every level combined with on-the-ground enumeration — is what distinguishes field-based multistage sampling from purely administrative or online sampling designs.