Uncertain geographic context problem

{{Short description|Source of statistical bias}}

The uncertain geographic context problem or UGCoP is a source of statistical bias that can significantly impact the results of spatial analysis when dealing with aggregate data.{{cite journal |last1=Kwan |first1=Mei-Po |title=The Uncertain Geographic Context Problem |journal=Annals of the Association of American Geographers |date=2012 |volume=102 |issue=5 |pages=958–968 |doi=10.1080/00045608.2012.687349|s2cid=52024592 }}{{cite journal |last1=Kwan |first1=Mei-Po |title=How GIS can help address the uncertain geographic context problem in social science research |journal=Annals of GIS |date=2012 |volume=18 |issue=4 |pages=245–255 |doi=10.1080/19475683.2012.727867 |bibcode=2012AnGIS..18..245K |s2cid=13215965 |url=https://www.tandfonline.com/doi/full/10.1080/19475683.2012.727867 |access-date=4 January 2023|url-access=subscription }}{{cite book |last1=Matthews |first1=Stephen A. |title=International Encyclopedia of Geography: People, the Earth, Environment and Technology: Uncertain Geographic Context Problem |date=2017 |publisher=Wiley |doi=10.1002/9781118786352.wbieg0599 |url=https://onlinelibrary.wiley.com/doi/10.1002/9781118786352.wbieg0599}} The UGCoP is very closely related to the Modifiable areal unit problem (MAUP), and like the MAUP, arises from how we divide the land into areal units.{{cite book |last1=Openshaw |first1=Stan |title=The Modifiable Aerial Unit Problem |date=1983 |publisher=GeoBooks |isbn=0-86094-134-5 |url=https://www.uio.no/studier/emner/sv/iss/SGO9010/openshaw1983.pdf}}{{cite journal |last1=Chen |first1=Xiang |last2=Ye |first2=Xinyue |last3=Widener |first3=Michael J. |last4=Delmelle |first4=Eric |last5=Kwan |first5=Mei-Po |last6=Shannon |first6=Jerry |last7=Racine |first7=Racine F. |last8=Adams |first8=Aaron |last9=Liang |first9=Lu |last10=Peng |first10=Jia |title=A systematic review of the modifiable areal unit problem (MAUP) in community food environmental research |journal=Urban Informatics |date=27 December 2022 |volume=1 |issue=1 |page=22 |doi=10.1007/s44212-022-00021-1 |s2cid=255206315 |doi-access=free |bibcode=2022UrbIn...1...22C }} It is caused by the difficulty, or impossibility, of understanding how phenomena under investigation (such as people within a census tract) in different enumeration units interact between enumeration units, and outside of a study area over time.{{cite journal |last1=Gao |first1=Fei |last2=Kihal |first2=Wahida |last3=Meur |first3=Nolwenn Le |last4=Souris |first4=Marc |last5=Deguen |first5=Séverine |title=Does the edge effect impact on the measure of spatial accessibility to healthcare providers? |journal=International Journal of Health Geographics |date=2017 |volume=16 |issue=1 |page=46 |doi=10.1186/s12942-017-0119-3 |pmid=29228961 |pmc=5725922 |doi-access=free }} It is particularly important to consider the UGCoP within the discipline of time geography, where phenomena under investigation can move between spatial enumeration units during the study period. Examples of research that needs to consider the UGCoP include food access and human mobility.{{cite journal |last1=Chen |first1=Xiang |last2=Kwan |first2=Mei-Po |title=Contextual Uncertainties, Human Mobility, and Perceived Food Environment: The Uncertain Geographic Context Problem in Food Access Research |journal=American Journal of Public Health |date=2015 |volume=105 |issue=9 |pages=1734–1737 |doi=10.2105/AJPH.2015.302792|pmid=26180982 |pmc=4539815 }}{{cite book |last1=Zhou |first1=Xingang |last2=Liu |first2=Jianzheng |last3=Gar On Yeh |first3=Anthony |last4=Yue |first4=Yang |last5=Li |first5=Weifeng |title=Advances in Spatial Data Handling and Analysis |chapter=The Uncertain Geographic Context Problem in Identifying Activity Centers Using Mobile Phone Positioning Data and Point of Interest Data |series=Advances in Geographic Information Science |date=2015 |pages=107–119 |doi=10.1007/978-3-319-19950-4_7|isbn=978-3-319-19949-8 }}File:Space-time prism 1500x1125.png diagram of a space-time prism, and on the left is a map of the potential path area for two different time budgets.{{cite journal |last1=Allen |first1=Jeff |title=Using Network Segments in the Visualization of Urban Isochrones |journal=Cartographica: The International Journal for Geographic Information and Geovisualization |date=2019 |volume=53 |issue=4 |pages=262–270 |doi=10.3138/cart.53.4.2018-0013|s2cid=133986477 }}]]

The uncertain geographic context problem, or UGCoP, was first coined by Dr. Mei-Po Kwan in 2012. The problem is highly related to the ecological fallacy, edge effect, and Modifiable areal unit problem (MAUP) in that, it relates to aggregate units as they apply to individuals. The crux of the problem is that the boundaries we use for aggregation are arbitrary and may not represent the actual neighborhood of the individuals within them. While a particular enumeration unit, such as a census tract, contains a person's location, they may cross its boundaries to work, go to school, and shop in completely different areas.{{cite journal |last1=Zhao |first1=Pengxiang |last2=Kwan |first2=Mei-Po |last3=Zhou |first3=Suhong |title=The Uncertain Geographic Context Problem in the Analysis of the Relationships between Obesity and the Built Environment in Guangzhou |journal=International Journal of Environmental Research and Public Health |date=2018 |volume=15 |issue=2 |page=308 |doi=10.3390/ijerph15020308 |pmid=29439392 |pmc=5858377 |doi-access=free }}{{cite book |last1=Zhou |first1=Xingang |last2=Liu |first2=Jianzheng |last3=Yeh |first3=Anthony Gar On |last4=Yue |first4=Yang |last5=Li |first5=Weifeng |title=Advances in Spatial Data Handling and Analysis |chapter=The Uncertain Geographic Context Problem in Identifying Activity Centers Using Mobile Phone Positioning Data and Point of Interest Data |series=Advances in Geographic Information Science |date=2015 |pages=107–119 |doi=10.1007/978-3-319-19950-4_7 |isbn=978-3-319-19949-8 |chapter-url=https://link.springer.com/chapter/10.1007/978-3-319-19950-4_7 |access-date=22 January 2023}} Thus, the geographic phenomena under investigation extends beyond the delineated boundary .{{cite journal |last1=Salvo |first1=Deborah |last2=Durand |first2=Casey P. |last3=Dooley |first3=Erin E. |last4=Johnson |first4=Ashleigh M. |last5=Oluyomi |first5=Abiodun |last6=Gabriel |first6=Kelley P. |last7=Van Dan Berg |first7=Alexandra |last8=Perez |first8=Adriana |last9=Kohl |first9=Harold W. |title=Reducing the Uncertain Geographic Context Problem in Physical Activity Research: The Houston TRAIN Study |journal=Medicine & Science in Sports & Exercise |date=June 2019 |volume=51 |issue=6S |pages=437 |doi=10.1249/01.mss.0000561808.49993.53|s2cid=198375226 }} Different individuals, or groups may have completely different activity spaces, making an enumeration unit that is relevant for one person meaningless to another.{{cite book |last1=Thrift |first1=Nigel |title=An Introduction to Time-Geography |date=1977 |publisher=Geo Abstracts, University of East Anglia |isbn=0-90224667-4 |url=https://alexsingleton.files.wordpress.com/2014/09/13-time-geography.pdf}} For example, a map that aggregates people by school districts will be more meaningful when studying a population of students than the general population.{{cite journal |last1=Shmool |first1=Jessie L. |last2=Johnson |first2=Isaac L. |last3=Dodson |first3=Zan M. |last4=Keene |first4=Robert |last5=Gradeck |first5=Robert |last6=Beach |first6=Scott R. |last7=Clougherty |first7=Jane E. |title=Developing a GIS-Based Online Survey Instrument to Elicit Perceived Neighborhood Geographies to Address the Uncertain Geographic Context Problem |journal=The Professional Geographer |date=2018 |volume=70 |issue=3 |pages=423–433 |doi=10.1080/00330124.2017.1416299 |bibcode=2018ProfG..70..423S |s2cid=135366460 |url=https://www.tandfonline.com/doi/abs/10.1080/00330124.2017.1416299 |access-date=22 January 2023|url-access=subscription }} Traditional spatial analysis, by necessity, treats each discrete areal unit as a self-contained neighborhood and does not consider the daily activity of crossing the boundaries.