Friday, April 8, 2011

Minority Distribution Maps

Minority population distributions have changed over time, partly because we have seen a growth in minority inflow to the region, and partly because of changes in race category definitions within the Census.

These 3 maps show the changes between the 1990, 2000, and 2010 censuses for the City of Utica and the surrounding area.

1990 Minority Distribution

2000 Minority Distribution

2010 Minority Distribution

Several things should be noted:

  1. Between 1990 and 2000 the Census changed how it recorded race data. No longer were people restricted to a single race category, but could select multiple races.
  2. Note how concentrated the areas with at least 25% of the population being of minority background was in the center of Utica. By 2000 the area had grown substantially to a large area surrounding that same core; by 2010 the minority population had expanded considerably into the West Utica neighborhoods.
  3. North Utica sees considerable minority growth in 2000; South Utica sees it's minority populations expand particularly in the last decade.

Friday, April 1, 2011

The Three Pillars of Census Based Data

When most people hear the words "Census Bureau" they only think of one thing - "the" census. Of course what they really mean is the "decennial" census, being that survey we all take once every 10 years as part of our constitutional duties. In reality the Census Bureau conducts a slew of surveys covering a wide range of topics. However, there are three that are interrelated that I want to review here. Because they are often confused with one another, it is important to understand how they differ and what that difference means for the data user.

The first is the data product mentioned above - the decennial census. The decennial census is conducted once every 10 years, administered officially on April 1 of any year ending in a zero. Historically the decennial census has been used to capture not just population counts but also to help flesh out the character of the people living in the country. It did this by offering two forms - a short form and a long form.

Understanding the American Communities Survey

In the past, every ten years the Census Bureau conducted our decennial census to provide information to Congress and policymakers about the country. This was done through two forms – the short form (with only 7 or 8 basic questions) and the long form (which had lots of questions on everything from income to education). 

Beginning in 2010, the decennial census will ONLY be done with the short form. In place of the long form, a new tool called the American Communities Survey was fully implemented in 2005. The American Community Survey (ACS) is a nationwide survey designed to provide communities a fresh look at how they are changing. 

With the ACS, the Census Bureau now collects and produces population and housing information every year, instead of every ten years. About three million housing unit addresses are sampled each year throughout the United States and Puerto Rico to produce this data. 

Beginning with the 2005 ACS (and continuing every year thereafter), a variety of demographic, social, economic and housing data for each year was made available for geographic areas with a population of 65,000 or more. These are called the “1 Year Estimates” – they are based on a single year’s sampling of our local population. Because these “1 Year Estimates” were only released for communities with populations of 65,000 or more, in our region this only covered Oneida County as a whole.

In 2008, however, the ACS released its first multi-year estimates based on ACS data collected from 2005 through 2007. These are called the “3 Year Estimates”. The “3 Year Estimates” of demographic, social, economic and housing characteristics are available for geographic areas with a population of 20,000 or more. For our region, this now means data are available for Oneida County, Herkimer County, Utica, Rome and the Town of New Hartford. 

This past December the Census released “5 Year Estimates”.  With their release, data is now available for ALL levels of geography, regardless of population size. These data cover the sample period of 2005 to 2009.

The 3-year and 5-year estimates require slightly different thinking about the data they contain. These 3-year estimates are called “period estimates”. So when discussing the child poverty data, for example, the best way to characterize this information would be along the following lines: “The child poverty rate for Oneida County over the period 2005 to 2007 was 'X' percent.”  These are NOT an average of 3 or 5 individual years; they are the average of a sample taken over 3 or 5 years.

Comparing the 3-year and 5 year estimates to other Census measures is possible, but with some caveats. Generally the following are good guidelines:

  1. If comparing across geographic areas (like between two towns or two counties), make sure you are comparing apples to apples.  That is, compare 1-year estimates to 1-year estimates, or 3-year estimates to 3-year estimates, and 5 year to 5 year estimates. DO NOT compare one-year estimates with three-year estimates across geographies.
  1. If comparing data for a single area (like just one town or one county to itself) over time, this can be done but it must be done with caution. Comparing the 2000 Census for Herkimer County to the 2005-2007 period estimate, for example, in Herkimer County is acceptable, but keep in mind there can  problems with differences in residency rules, reference period differences, and question wording changes.
  1. If you are more interested in current data, 1-year or 3 year estimates are the better source to use; if precision is more important, then use the 5-year estimates. The five year estimates represent a larger sample size over a longer period of time so they have more reliability, especially for smaller areas.
A good source for what is and isn’t comparable when using the ACS data sets is found here or by going to the Census Bureau website at: . The site url is case sensitive so be sure to use lower and upper case letters as in the address listed for the site.