Household Characteristics

Inputs

Input	Module Source	Usage
MGRA cross-reference ([inputs].[mgra])	Startup	Used to merge MGRA-level values with census tract rates
Households in each MGRA ([outputs].[hh])	Housing and Households	Used to generate household characteristics
Household population in each MGRA ([outputs].[hhp])	Housing and Households	Used to balance household size implied household population
Census tract household income distribution	External (ACS)	Apply to households to create households by income categories
Census tract households by size distribution	External (ACS)	Apply to households to create households by size categories

MGRA cross-reference ([inputs].[mgra])

See Startup.

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

See Housing and Households.

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

See Housing and Households.

Census tract household income distribution

The household income distribution is derived from American Community Survey (ACS) table B19001 | HOUSEHOLD INCOME IN THE PAST 12 MONTHS. The table provides households by household income. Dividing each category by total households provides census tract household income distributions. The year of the ACS table provides the inflation-adjusted dollars year.

$$\forall t \in \text{San Diego Tracts}, \forall hhi \in \text{Household Income Category}; \text{Distribution}_{t,hhi} = \frac{\text{Households in Income Category}_{t,hhi}}{\text{Households}_t}$$

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

$$\forall hhi \in \text{Household Income Category}; \text{Regional Household Income Distribution}_{hhi} = \frac{\sum \text{Households in Income Category}_{hhi}}{\sum \text{Households}}$$

Census tract households by size distribution

The households by size distribution is derived from ACS table B11016 | HOUSEHOLD TYPE BY HOUSEHOLD SIZE. The table provides households by household size category. Dividing each category by total households provides census tract households by size distributions.

$$\forall t \in \text{San Diego Tracts}, \forall hhs \in \text{Household Size Category}; \text{Distribution}_{t,hhs} = \frac{\text{Households in Size Category}_{t,hhs}}{\text{Households}_t}$$

To avoid division by zero errors, the households by size distribution is set to NULL if the 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 households by size distribution while SANDAG's LUDU contains housing units. In this situation, the regional households by size distribution is used.

$$\forall hhs \in \text{Household Size Category}; \text{Regional Household Size Distribution}_{hhs} = \frac{\sum \text{Households in Size Category}_{hhs}}{\sum \text{Households}}$$

Outputs ([outputs].[hh_characteristics])

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)
[metric]	Household characteristic category
[value]	Number of households

Households by income category in each MGRA

MGRA households by income category. Calculated by applying census tract distributions to households.

Households by size category in each MGRA

MGRA households by size category. Calculated by applying census tract distributions to households. Adjusts size categories within MGRAs such that the implied household population range (min-max) contains the actual MGRA household population value.

For example, within a MGRA with 10 households of size one, 10 households of size two, ..., 10 households of size 7+, the minimum amount of household population would be 1x10 + 2x20 + ... + 7x10 = 280. The maximum amount of household population, assuming the 7+ category all average 11 people (see issue #112), would be 1x10 + 2x20 + ... + 11x10 = 320. The actual amount of household population in this MGRA must be between these two values. If it is not, the households in size categories are adjusted until the condition is satisfied.