Population by Type

Inputs

Input	Module Source	Usage
MGRA Geography ([inputs].[mgra])	Startup	Used to merge MGRA-level values with census tract rates and jurisdiction controls
Special MGRAs ([inputs].[special_mgras])	Startup	Identifies "Group Quarters - Institutional Correctional Facilities"
MGRA Cross References	Demographic Warehouse	Provides cross reference from MGRAs to census tracts and jurisdictions
Point geometry group quarters by type	External (LUDU)	Generate counts of group quarters by type within each MGRA
Jurisdiction total group quarters controls	External (DOF)	Apply to group quarters to match total group quarters by jurisdiction
Households in each MGRA ([outputs].[hh])	Housing and Households	Used to generate household population
Census tract average household size	External (ACS)	Apply to households to create household population
Jurisdiction household population controls	External (DOF)	Adjust household population to match household population by jurisdiction

MGRA Geography ([inputs].[mgra])

See Startup.

Special MGRAs ([inputs].[special_mgras])

See Startup.

MGRA Cross References

See private SANDAG repository Demographic Warehouse.

Point geometry group quarters by type

MGRA group quarters by type is aggregated from SANDAG's point geometry group quarters dataset to the MGRA-level. To ensure that group quarters by type is assigned to the correct MGRA, a spatial join is used to match the group quarters point geometries to MGRA polygons. The special MGRAs table ([inputs].[special_mgras]) is used to identify instances of "Group Quarters - Other" that should be mapped to "Group Quarters - Institutional Correctional Facilities".

Jurisdiction total group quarters controls

Jurisdiction-level total group quarters controls are directly pulled from the California Department of Finance (DOF) Estimates. For years 2010-2019, data is pulled from the most recent E-8 product at the time. For years 2020+, data is pulled from the most recent E-5 product at the time.

Households in each MGRA ([outputs].[hh])

See Housing and Households.

Census tract average household size

Average household size is derived from two American Community Survey (ACS) tables, B25032 | TENURE BY UNITS IN STRUCTURE, and B11002 | HOUSEHOLD TYPE BY RELATIVES AND NONRELATIVES FOR POPULATION IN HOUSEHOLDS. The first table provides households. The second table provides household population. Dividing the two provides census tract average household size.

$$\forall t \in \text{San Diego Tracts}; \text{Household Size}_t = \frac{\text{Household Population}_t}{\text{Households}_t}$$

To avoid division by zero errors, the average household size is set to NULL if households are zero within a census tract. This can lead to conflict between ACS data and SANDAG's LUDU. Within a census tract, the ACS may have no housing units, no households, and a NULL average household size while SANDAG's LUDU contains housing units. In this situation, the regional average household size is used.

$$\text{Regional Household Size} = \frac{\sum \text{Household Population}}{\sum \text{Households}}$$

Jurisdiction household population controls

Jurisdiction-level household population controls are directly pulled from the California Department of Finance (DOF) Estimates. For years 2010-2019, data is pulled from the most recent E-8 product at the time. For years 2020+, data is pulled from the most recent E-5 product at the time.

Outputs

Population by housing type in each MGRA

MGRA population by housing type. Group quarters housing types are calculated by aggregating group quarters points to MGRAs, then controlling overall group quarters at the jurisdiction-level to DOF controls. Household population is calculated by taking MGRA households, applying census tract average household sizes, then controlling household population at the jurisdiction-level to DOF controls.

Group Quarters population by housing type in each MGRA ([outputs].[gq])

Each row of this table contains the following information:

Column	Description
[run_id]	Estimates run identifier
[year]	Year within estimates run
[mgra]	The Master Geographic Reference Area (MGRA)
[gq_type]	Group quarters housing type
[value]	Number of persons living in group quarters

Household population in each MGRA ([outputs].[hhp])

Each row of this table contains the following information:

Column	Description
[run_id]	Estimates run identifier
[year]	Year within estimates run
[mgra]	The Master Geographic Reference Area (MGRA)
[value]	Household population