Quick Facts:
Scan/US MicroGrids

• 2+ million grids covering only populated areas

• 3 Micro Grid Sizes (determined by household densisty), ranging from 1 square mile down to 1/16 square mile

• Demographic data provided for each grid object

• Instant data summaries for rings, polygons & contours

Scan/US MicroGrids are better at showing population change than either Census Block Groups, or Census Blocks.

This three-section appendix shows you how MicroGrids are better.  First we present an overview, and then, in a more detailed look, we compare the MicroGrid view of households on the ground , compared with the BG/Block depiction.  Finally we discuss one grid in detail.

1. The Study Area

Our 'study area' is a four block-group area in Santa Clarita, CA.  This area illustrates how Scan/US shows change with its proprietary MicroGrid geography.

As of 2000, US Census records 12 households in these four block groups. The Scan/US 2010 mid-year estimates show 2,835 households in residence, 90% of them new since 2005.

Four Census block-groups showing streets based on
TIGER 2009 streets

A 2009 satellite image shows the extent of development that is revealed in the Scan/US 2010 estimates.
(Google Earth photo)

This table summarizes the residential development in this 1.64 square mile area between 2000 and 2010.

Using Zip+4 segment points, Scan/US tracks the placement of residential change more accurately than Census block groups or Census blocks.

Zip+4 segments are the basic units of the postal delivery system. Scan/US MicroGrid cartography, summarizing data from Zip+4 segments, brings residential change into focus at the resolution of 1/16^th of a square mile.

The study area contains 4 block groups, 12 blocks, 25 MicroGrids and 274 Zip+4 segments. Residential saturation data (“drop counts”) for Zip+4s provide the data points for distributing block group estimates of household counts.  How is this done?

First the drop counts of the blocks within a block group are normalized and used as weights to distribute the block group’s updated demographics to the blocks.  The resulting detailed demographics for the blocks are then rebalanced to conform to the parent block group’s demographic profile.  The distribution of the balanced block updates to the MicroGrids is accomplished by using the current Zip+4 drop counts to calculate the proportion of block demographics that are to be assigned to the overlapping grids.

The MicroGrid highlighted on the map derives all of its characteristics from one block but the MicroGrid overlay of the study area shows that, in many cases, multiple blocks and block groups contribute to a particular grid’s demographic profile.

Scan/US MicroGrids (blue grid) and Zip+4 segments (purple diamonds) superimposed on Census 2000 block groups

3. Focus on MicroGrid 34118/2734.34

This grid contains the 16 Zip+4s listed below, along with their April 2010 “Drop Counts”.

The Zip+4 drop counts indicate where, how much and what type of development exists right down to a specific address range on a street. 

The table below shows the four separate counts that are available for each Zip+4: single family (Napt), multi-family (Apt), business (Bus) and seasonal (Seas).  These drop counts tell us that this MicroGrid neighborhood is made up of exclusively single family dwellings. 

The satellite photo below shows the 16 Zip+4s overlaid by the grid.  (The image was created using Scan/US “Locate in Google Earth,” a standard feature of the Scan/US software).

The 16 Zip+4 markers on the image pinpoint the housing associated with the drop counts. The “TotRes” drop count approximates “total housing units” not “occupied housing units” or households.  A cursory rooftop count of the housing seen in this satellite image of the grid comes to 120 housing units (as of the date of the image) compared to the “TotRes” counts of grid total of 170. The Scan/US 2010 balanced estimate of total housing units in the grid is 108 units.

This grid is roughly 1/16^th of a square mile in size and is estimated to contain 99 households with an average size of 3.10 persons; median household income is $57,790, and an annual aggregate household income of $6,440,000.