FAQs (Frequently Asked Questions)

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What is a ZCTA?

ZIP Code Tabulation Areas (ZCTAs) were developed for the 2000 Census by the US Census Bureau for tabulating summary statistics for ZIP Code-like areas. Recognizing the fact that most people do not identify with census tracts or other census geography, the ZCTAs were created as generalized representations of US Postal Service ZIP Codes. Currently, each ZCTA is built by aggregating Census 2010 blocks, whose addresses use a given ZIP Code, into a ZCTA which gets that ZIP Code assigned as its ZCTA code. While in most instances the ZCTA code equals the ZIP Code for an area, not all ZIP Codes have their own ZCTA. The UDS Mapper contains updated national ZCTAs reflecting U.S. Postal Service ZIP Code changes through October, 2010; there may be no further updates of ZCTA boundaries until required for the 2020 Census. See http://www.census.gov/geo/reference/zctas.html for more information. In their annual preparation of Uniform Data System data from health centers, John Snow, Inc. assures that every valid ZIP Code maps to the ZCTA that best fits its location (based on centroid). Therefore, reported UDS patients are not lost due to new or changed ZIP Codes.

What is a 'Health Center Program (HCP) grantee'?

The terms 'Health Center Program grantee' or 'HCP grantee', as used within the UDS Mapper site, refer to a public or private non-profit health care organization that meets certain criteria under the Medicare and Medicaid Programs (respectively, Sections 1861(aa)(4) and 1905(l)(2)(B) of the Social Security Act), receives funds under the Bureau of Primary Health Care Health Center Program (Section 330 of the Public Health Service Act), and reports data to the Uniform Data System (UDS) that subsequently are sent to John Snow, Inc. for analysis (i.e., Community Health Centers, Migrant Health Centers, Healthcare for the Homeless Programs, and Public Housing Primary Care Programs). For additional information on HCP grantees, see HRSA's web page on Health Centers.

Why are the data only displayed by ZIP Code Tabulation Area (ZCTA)?

First, Health Center Program (HCP) grantees and look-alikes (collectively referred to as "health centers") report their patients to the BPHC (in the Uniform Data System) by their ZIP Code of origin. Second, no demographic data are available describing ZIP Codes as they are constructed by the US Postal Service, so the U.S. Census Bureau, for the first time in 2000, developed a methodology for providing statistically relevant data that approximate the existing ZIP Codes by creating ZIP Code Tabulation Areas (ZCTAs) which generally are meant to cover one or more ZIP Codes. By aggregating the health center patients by ZIP Code to the ZCTA level, it is possible to compare the number of patients to the population. For national or state-level Uniform Data System data, please visit the following HRSA website: http://www.hrsa.gov/data-statistics/health-center-data/index.html.

Why can't I see my ZIP Code on the map?

The UDS Mapper displays ZCTAs, not ZIP Codes. ZCTAs are the US Census Bureau's approximation of ZIP Codes, and while in most instances the ZCTA code equals the ZIP Code for an area, not all ZIP Codes have their own ZCTA. The UDS Mapper contains updated national ZCTAs reflecting U.S. Postal Service ZIP Code changes through October, 2010, and there may not be any further updates of ZCTA boundaries until required for the 2020 Census. Therefore, since US Postal Service ZIP Codes can change at any time as needed for efficient delivery of the mail, ZIP Codes exist that have not been converted to ZCTAs. To address this issue, in their annual preparation of Uniform Data System data from health centers, John Snow, Inc. assures that every valid ZIP Code maps to the ZCTA that best fits its location. Therefore, reported UDS patients are never left out of counts/analyses due to new or changed ZIP Codes.

Note: within the reference geography (e.g., reflected in the search and zoom functions) underlying this tool, ZIP Codes are included. Therefore, you can enter a ZIP Code that is not a ZCTA and zoom to that area, but may not see the ZIP Code number or area represented on the map. This is because there is no ZCTA for that ZIP Code. Although you will be seeing the correct area, it will not be labeled as such. If you do not see your ZIP code in the UDS Mapper, please use the ZIP Code to ZCTA crosswalk tool available within the UDS Mapper.

What Uniform Data System data are used in the UDS Mapper?

Health Center Program (HCP) grantees and look-alikes (collectively referred to as "health centers") report the number of patients they see by ZIP Code in one table of the Uniform Data System (UDS). Data from this one table are displayed by ZCTA within the UDS Mapper site and come only from health centers that have reported data to the UDS, and whose data were subsequently provided to and analyzed by John Snow, Inc. (i.e., Community Health Centers, Migrant Health Centers, Healthcare for the Homeless Programs, and Public Housing Primary Care Programs). Therefore, the data by ZCTA within the site do not come from Rural Health Centers, NHSC sites, tribal organizations, etc. The current UDS ZIP Code level data used are from reporting year 2012.

Why are some of the patient counts for prior years different than they were last year?

JSI recalculated prior years data to match the 2010 ZCTA definitions to permit comparability and therefore patient numbers may not match those reported for prior years which were based on 2000 ZCTA definitions.

Why are there some ZCTAs with more than 100% penetration of the population?

There are three scenarios where a penetration rate (particularly for the low-income) can exceed 100%:
  1. Health centers in the area serve a significant population at/above 200% of poverty (and the UDS doesn't distinguish patients within ZIP Codes by income level)
  2. Multiple health centers are serving the same individuals (particularly an issue where one health center provides a non-medical service, such as dental, for a broad area)
  3. Health centers may serve large numbers of transient groups which may not be well-counted by Census (students, migrants, homeless, etc.)
The first of these is the probably the biggest issue in most cases. Theoretically if the penetration goes over 100% of the population it should be true that the health centers would first assure access for the low-income before serving those of higher income, for whom they can't apply the sliding fee scale anyway. It is important to note that 93% of health center patients of known income are below 200% of poverty nationally and we can't readily extrapolate from a health center's overall poverty mix as many health centers report a significant number of users of unknown income (approximately 23% of patients nationally). Conversely, it would not necessarily be true that every member of the low-income population would be expected to have a visit in the past year, so this may mean the denominator is higher than ideal as well. The issue is well understood and doesn't fundamentally change the basic utility of the calculation in assessing the role of health centers in serving the community. The data should be considered the starting point for considering this issue, not the final answer.

Note: It is true that rural centers are more likely to be serving those at/above 200% of poverty (because the issue is overall access not financial access) but we can still assume they will be making a priority of providing access to the low-income in the area, for whom they can offer sliding fee, before serving those of greater means where the sliding fee scale doesn't apply. Thus, if the number of health center patients exceeds the total low-income population, one can hopefully assume that the access needs for the low-income are being met. Also, there is a penetration rate amongst the total population calculated which may be more reflective of the role of a health center in a rural or frontier area.

Why aren't there more zooming options/extents?

The Main Maps of the UDS Mapper are based on tiles. At the highest level of zoom, only one tile is needed to represent the whole surface of the earth. As you zoom in closer to the map more tiles are needed for each additional level of zoom. Collectively the number of tiles grows exponentially and becomes prohibitive to store and serve the data.

Can I add additional information or drawings to the map?

Yes; click the 'Draw' button at the top right of the map area to add drawings, points, lines, shapes, and text.

Can I export the map on the screen to a PDF file?

Yes; a completed map can be exported by clicking the 'Print' button at the top right of the map area.

Can I export the raw data of the map that I am viewing?

You can see much of the data you are viewing (by ZCTA) in the 'Data' tab; this tab is located above the map on the left side of the screen. Once on that view of the UDS Mapper, you can export the data by clicking the Export icon at the top right of the screen. There is also a way to download whole states or whole counties worth of data by going to the Tutorials & Resources section of the website and clicking 'Download State/County Data by ZCTA Approximation'.

How do I print the map on the screen?

A map can be printed directly from the mapping screen by clicking the 'Print' button at the top right of the screen. The map and legend will be included in your printed document.

How do I see Alaska, Hawaii, or Puerto Rico?

You can manually zoom and drag the map to where these locations can be found on the map. You can also roll your mouse over the gray tabs in the upper left corner of the map to see the names of locations and click to zoom; Alaska is the top gray tab, Hawaii is the second gray tab from the top, and Puerto Rico is the third tab from the top. Alternately, using the Explore Service Area tool, search for Alaska, Hawaii, Puerto Rico, or any location within those states and territory and 'Go' to zoom in to that area.

What does the light gray color on the map represent?

If you have not selected any 'Background' options, the default color for the background is light gray. Therefore this gray color in the first eight Main Maps represents ZCTAs that have no data. Having no data may mean there were no reported health center patients, health centers that have reported patients did not have 11 or more patients in a given ZCTA, and/or the ZCTAs have no residents at all. In the Total Population Statistics Main Maps (representing only ACS 2007-2011 data) the gray color represents ZCTAs that do not have any residents at all.

When I try to use the Mapper or go to the 'Home' screen, it says I need to update Adobe Flash, is this necessary?

Yes, the mapping tool requires Adobe Flash to function; you can find a free update/download at the Adobe Flash website.

How do I export data in the Data Table view to a .CSV file?

To export the data in the Data Table view to a .CSV (comma separated value) file click the Export icon at the top right of the screen (while you are in the Data Table view). Depending on your internet browser preferences, you may be asked to save the file to your computer and/or may need to add a .csv extension to the file name when or after saving the file to your computer. Once downloaded, a .csv file can be opened in Microsoft Excel.

I forgot my password or would otherwise like to change it. How do I reset it?

If you have forgotten your password you can go to the homepage (www.udsmapper.org), click Login (in the upper right corner), and click forgot password. Enter the same email address you used when registering for the UDS Mapper, click Submit, and an email will be sent to you providing a temporary password, which you can then use to login. Once you are logged in using the temporary or current password, go to My Profile under the Help tab, change your password to your preference, and click Submit.

Why aren't there any check boxes next to the list of Main Maps?

Unlike the 'Optional' layers, where multiple items can be turned on at once, only one 'Main Map' can be viewed at a time.

When I scrolled over one ZCTA it said that '4' health centers were serving it; but I see on the map that 3 health center locations are within the ZCTA boundary; where is the fourth health center?

The number of health centers serving patients that live in a particular ZCTA refers to the number of health centers that people who live in a ZCTA travel to for services, not how many locations are physically located in a ZCTA. Keep in mind that within this tool there is no way to verify which health centers are serving that ZCTA beyond the five with the largest share of health center patients in that ZCTA.

What are the password requirements for the UDS Mapper?

Your password must be a minimum of 8 characters, including one or more uppercase letters, one or more lower case letters, and one or more numbers.