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Tessellation is the process Place Forecast uses to downscale ABS data to mesh blocks. It distributes data from larger areas like SA1s and SA2s down to each mesh block. The weight depends on what the data counts. Place Forecast uses resident population as the weight for person-based data, such as country of birth, language, year of arrival, and marital status. It uses dwelling counts for dwelling- or household-based data, such as census dwellings and household type. Once the data is downscaled to mesh blocks, Place Forecast then aggregates the mesh block data to small areas. Each mesh block is matched to a small area based on where their boundaries overlap. All data for each mesh block, such as population, dwellings, births, deaths, in-migrations, and out-migrations, flows into the small area's totals.
Place Forecast can split a mesh block across two or more small areas. This means small area boundaries do not have to follow mesh block edges. Users can define small areas in any shape they need, and the system will cut mesh blocks to fit.
Mesh blocks also link to SA1s and SA2s, but through their ABS codes rather than boundary overlap. In all cases, no person or dwelling is counted twice, and none is left out.