About EASI


Who is EASI?

EASI is a New York-based independent developer and marketer of CD ROM and Internet demographic data and software solutions that provide simple to interpret demographic reports with unique search and analysis tools. EASI provides targeted site analysis and demographic reference software that is easy to use, designed and priced for any value-conscious business.

Methodology for Updates

The following is a general description of the methodology used by EASI to update the demographic and economic characteristics for the United States, States, Counties, ZIP Codes, Census Tracts, Block Groups, and ZIP Plus 4's.

The purpose of this explanation is not to divulge any proprietary methods but to illustrate the efforts made on your behalf to create accurate updates. EASI statistician's and programmers have over twenty five years of experience updating these types of data. By industry standard these estimates would be considered of the highest quality.

Input Files
  1. Benchmark data are from the 1990 Census Summary File 3; created by the Bureau of the Census and covers a wide variety of social and economic characteristics of the population by County, ZIP Code, Census Tract, and Block Group.
  2. EASI has collected from the Census Bureau all current updates and estimates for a variety of key demographic information. This information is both for national and for local areas (usually Counties). All these official estimates have been analyzed and incorporated into our estimates.
  3. EASI has summarized from the United States Postal Service (USPS) mailable households at a County, ZIP Code, Census Tract, and Block Group level. These data have been used as the primary input to estimate local current change within a small area such as a Block Group.
  4. The data match starts by identifying for every ZIP Plus 4 (ZIP+4), which Block Group it belongs to. EASI has analyzed mailable households at the ZIP Plus 4 level, using the latest Tiger file, to determine which Block Group (primary) they should be assigned to. One of the key goals is to identify all correct ZIP Codes and ZIP+4's and then assign them to the correct Block Group that these mailable Households should be assigned to.
Data Preparation
The steps in creating the ZIP Plus 4 (ZIP+4 ) and Block Group mailable Households include:

  1. Start with the quarterly USPS ZIP+4 file. This file (December 1997) includes all valid ZIP+4's in the country.
  2. For each ZIP+4's, we add Census Blocks Groups based upon the Tiger file. Approximately 20 million records are processed by this direct match (about 75%).
  3. For each remaining ZIP+4, we match against our internal geocode file (latitude and longitude). This file is based on running through address matching/geocoding software. Approximately 180f total are matched to their Block Group this way.
  4. For each remaining ZIP+4 that cannot be geocoded by b) or c), we use a calculated carrier route or Block Group centroid. We weight the geographies to a larger area and calculate a latitude and longitude. We then determine which is the closest (distance) Block Group. This is done for approximately 50f total.
  5. If still unassigned then, we use nearest neighbor ZIP+4. There are approximately 20r total are done through this approach (recent, 6 months old ZIP+4s are often in this category).
  6. Block Groups assigned are from the most recent Census Tiger file. Tiger errors, where identified (such as wrong FIPS Codes) have been corrected.
  7. ZIP Plus 4's are assigned data based upon the data of the Block Group that it has been assigned to. (Note: There are no official Census Bureau data for ZIP+4.)
Analysis
  1. EASI has developed a series of models which uses the relationship between the current mailable households at the Block Group level to estimate relationships compared to the county. EASI analyzes the change in relationships between these mailable households over time and compared to the county using a proprietary formula.
  2. County estimates have been related to any current county information (P-25 and P-26) from the Census Bureau and also to available national trends. EASI has also used data from the CPS (Current Population Survey) and the Annual Housing Survey (AHS) and also from directly from the Census Bureau.
  3. Additional updating sources include: Postal Office AMS files and Postal bulletins (the ZIP Alert); these record any changes that take place to ZIP codes including name changes, delivery or branch changes as they become official. Other sources include: U.S. Postal Service City-State File (monthly) and Delivery Statistics File. These CD ROM's incorporate main inventory of ZIP Codes and the post office and other names associated with them.
  4. Updates and 5 year projections are done at the county level and at the Block Group level. The Block Group data will add to the separately generated county data. Other geographies are summarized from the Block Group level (e.g. Block Groups are added up to create Census Tracts).
Consistency - year to year changes.
  1. Each year EASI uses all available sources to maintain the highest quality of our estimates. Sometimes this new information will makes year to year changes less meaningful. That is, the changes from our 5 year forecast are consistent from the 1998 estimate but changes from last's years estimates are not necessarily so. With some data sources information becomes available annually but with others data elements may not be released but once every two or three years. As data becomes available and is usable EASI incorporates the results into our estimates.
  2. User should note that ZIP Code areas change from year to year (EASI assigns a portion of each Block Group to a ZIP Code). It should be noted that there are many vendors who supply ZIP Code to Block Group definitions. (Note: While EASI uses one for our source, EASI can convert our ZIP Code data to virtually any source if required.)
  3. In addition, with the 1998 release, EASI has modified the definition of our income estimates. In prior years EASI used the same definition as in the Census. With this release EASI is switching to Money Income which will result, generally, in a higher estimate of income than in prior years. (The change has been made based upon input from our users.) The data for the 5 year projections will be consistent. Users who compare our current data to last year should take care especially with the income data. These changes also affect the income distribution.
Accuracy
  1. With all estimates and with ours as well, the higher the level of data (national is the highest) the more accurate the estimate. Our data follows standard demographic techniques, all developed with over 25 years of experience. It is highly accurate and based upon the information we have obtained.
  2. EASI data has also been "field tested". That is, portions of our updated data are available at our web site and have been used by hundreds of thousands of users. These users raise questions about our updates, which we investigate. This input does help us to review and check results and makes our estimates better.