New Mexico Tribal Areas and Secure Tribal Queries
- Tribal Sovereignty The New Mexico Department of Health recognizes that data will be shared with each specific tribe with respect to the sovereignty of these nations. Sharing data on events within the geographic boundary of tribe is consistent with the "Public Health Authority" of that tribe.
- Tribal Public Authority The New Mexico Department of Health recognizes the authority of tribal government to conduct public health activities on behalf of all people living inside of tribal boundaries.
Before this project, the New Mexico Department of Health reported tribal data based only on self-reported tribal affiliation. Reporting data in this way is insufficient the analysis by tribal communities. The New Mexico Department of Health recognizes a need to geographically identify tribal data to improve the way that these data are reported and shared with respective tribes. The secure tribal queries within the NM IBIS website allow for the analysis of tribal geographically as well as by self reported tribal affiliation (within a given geography). These queries have been developed with the goals of improving data sharing between tribes and the NM DOH, as well as improving tribal community health assessment.
Methodology
Selection of Tribal Boundaries
The United States Census Bureau collects data on geographies called "American Indian, Alaska Native, and Native Hawaiian Areas". The boundaries that were used to develop the secure queries found on the NM IBIS website are all classified by the United States Census as "American Indian Areas (Federal)/ Off-Reservation Trust Lands" with the exception of the three Navajo Chapters of Alamo, Ramah and To'hajiilee. Navajo Chapters are considered to be "Tribal Subdivisions" by the US Census. These communities are included in the NM IBIS secure tribal queries due to a demand for data specific to these non-contiguous Navajo Chapters. Additionally, the Ute Mountain Ute tribe and the Fort Sill Apache tribe were not included in these because these tribes are not known to have any members living within the New Mexico border. The boundaries of the Navajo Nation and Zuni Pueblo cross New Mexico. These queries only include data pertaining to events geocoded within the New Mexico border, as the New Mexico Department of Health is unable to provide data that fall under the jurisdiction of other states. Below is a diagram of the hierarchy of AIAN areas collected by the US census, and a map of the tribal boundaries that are used in this analysis. The tribal boundaries used in this analysis were downloaded from the US Census TIGER/Shapefile website.
Geocoding and Assignment of Records to Tribal Areas
Data for a given New Mexico Tribal Area was derived by attempting to geocode the residential address associated with each event. Geocoding assigns each address an x and y coordinate that corresponds to the Earth's latitude and longitude. The accuracy and precision of the geocoding process depends on having a complete and correct address associated with every event that could be matched uniquely to a standardized address in a geodatabase that provided the needed geographic coordinates. Records such as P.O boxes or rural routes that could not be matched to a standardized address were geocoded with the most precise alternate geocode available. Often this was the geocode of a nearby intersection, or the geographic centroid of the ZIP code, populated place, or county referenced in the address. Certain conditions make it difficult to precisely geocode every record, including:
- Missing or incorrect street numbers
- Missing, misspelled, or non-standard street names
- Use of a post office box only
- Use of a rural route, highway contract route or general delivery address
Imprecise geocoding makes it difficult to assign records to tribal areas. In addition, there are several characteristics of tribal boundaries that also need to be considered in this analysis. Some of the conditions that make it difficult to assign records to tribal areas are:
- "Checker-board" tribal boundaries
- Overlapping tribal boundaries called "joint off-reservation trust areas"
- Records geocoded to ZIP code centroids that cross tribal boundaries
Events geocoded to addresses within areas designated for joint reservation use were not assigned to tribal areas. The precision of address level geocoding allows us to assume that these records do not fall under the public health authority of any one specific tribe. For events geocoded to ZIP code centroids, we used self reported tribal affiliation as a secondary criteria to improve the assignment of records to tribal areas. The birth and death records from the New Mexico Department of Health include self reported tribal affiliation. Records that included a self reported tribal affiliation and geocoded to ZIP code were assigned to the tribal area of the tribe with which they were affiliated. This was only done for records where the self reported tribal affiliation matched the tribe of the tribal area that were crossed by the ZIP code in question. Self reported tribal affiliation was chosen as a secondary criteria because this method is easily replicable in any data sets that include both geospatial data and tribal affiliation. The table below displays how death records with a self reported race/ethnicity of American Indian included self reported tribal affiliation, and how these records were assigned to Tribal Areas.
For the birth and death records, the geocoding work was performed by the Earth Data Analysis Center at the University of New Mexico. For death records period 1999-2011, there were 6100 records geocoded to addresses within tribal boundaries and another 9703 records geocoded to ZIP code centroids of ZIP code areas that cross tribal boundaries. (The U.S.Census Bureau ZIP Code Tabulation Area, or ZCTA, boundaries were used to define each ZIP code area for these purposes.) The diagram below is a visual depiction of how the 9703 death records geocoded to ZIP code centroids were assigned to tribal versus non-tribal areas.
Due to the possibility of misclassification due incomplete addresses, please use these data
with caution and include the following caveat along with any report of your results:
*****Important! New Mexico Department of Health Geocoding (Tribal and Small Areas) Caveat:*****
The method used to define tribal areas in New Mexico (as with all methods considered) has advantages and disadvantages. The New Mexico Department of Health carefully considered available methods and has taken great care to minimize all sources of error in the results. However, persons and organizations who use the New Mexico Tribal Area data results should take note that some areas in this analysis contain area misclassification errors as a result of imprecision in the geocoding of source data. Misclassification of data records will result in calculated rates that are higher or lower than the actual rate in that area. Misclassification errors are more likely to occur in rural areas of the state, but may occur in any of the 27 New Mexico Tribal areas. The NM Department of Health is currently evaluating the extent and impact of these errors. Please use the results with caution and evaluate whether the data results are consistent with other area characteristics (such as income and education levels and other risk factors).
The method used to define tribal areas in New Mexico (as with all methods considered) has advantages and disadvantages. The New Mexico Department of Health carefully considered available methods and has taken great care to minimize all sources of error in the results. However, persons and organizations who use the New Mexico Tribal Area data results should take note that some areas in this analysis contain area misclassification errors as a result of imprecision in the geocoding of source data. Misclassification of data records will result in calculated rates that are higher or lower than the actual rate in that area. Misclassification errors are more likely to occur in rural areas of the state, but may occur in any of the 27 New Mexico Tribal areas. The NM Department of Health is currently evaluating the extent and impact of these errors. Please use the results with caution and evaluate whether the data results are consistent with other area characteristics (such as income and education levels and other risk factors).
Reference Maps and Other Resources
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Secure Tribal Queries
Tribal data collected by the New Mexico Department of Health are treated similar to Protected Health Information (PHI). For this reason data that identifies a record as tribal (either geographically or by self-reported tribal affiliation) may only be released to the identified tribe. The New Mexico Department of Health considers all records within a tribal boundary to be under the Public Health Authority of that tribe. In order to aid with the analysis of tribal data, these queries allow the user to run separate queries on the records by affiliation as well, as long as the affiliation reported matches the tribal area. Access to secure tribal queries is only given to tribal representatives interested in accessing data pertaining to the tribe these persons or organizations represent. For questions and data requests, please contact the New Mexico Department of Health representative listed below.
New Mexico Department of Health Tribal Epidemiology Partner Organizations
Albuquerque Area Southwest Tribal Epidemiology Center
Navajo Nation Tribal Epidemiology Center
Questions, Requests or Concerns?
Please contact Samuel Swift, Tribal Epidemiologist
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