How do you document GIS data limitations?

1 Identify the sources of limitations

The first step in documenting GIS data limitations is to identify the sources of the limitations. These can be classified into three categories: data, method, and user. Data limitations refer to the inherent characteristics of the data, such as the resolution, accuracy, completeness, currency, and consistency. Method limitations refer to the procedures and techniques used to collect, process, analyze, and display the data, such as the sampling design, data conversion, data integration, spatial analysis, and visualization. User limitations refer to the expectations and assumptions of the data users, such as the purpose, scope, scale, and context of the data use.

2 Describe the impacts of limitations

The second step in documenting GIS data limitations is to describe the impacts of the limitations on the data quality and accuracy. This involves assessing how the limitations affect the spatial representation, measurement, relationship, and inference of the data. For example, a data limitation such as coarse resolution may impact the spatial representation by reducing the level of detail and introducing generalization errors. A method limitation such as a projection transformation may impact the measurement by introducing distortion and scale variation. A user limitation such as a mismatched scale may impact the relationship by creating false or missing associations between features. A limitation such as incomplete metadata may impact the inference by obscuring the data source, lineage, and reliability.

3 Provide recommendations for limitations

The third step in documenting GIS data limitations is to provide recommendations for how to address or mitigate the limitations. This involves suggesting ways to improve the data quality and accuracy, to reduce the uncertainty and error, and to enhance the data usability and value. For example, a recommendation for a data limitation such as low accuracy may be to use a more precise data collection method or to apply a correction factor. A recommendation for a method limitation such as a complex analysis may be to use a simpler or more robust technique or to validate the results with other sources. A recommendation for a user limitation such as a vague purpose may be to clarify the objectives and criteria of the data use or to consult with experts or stakeholders.

4 Format the documentation

The fourth step in documenting GIS data limitations is to format the documentation in a clear and consistent way. This involves choosing a suitable format, such as a report, a table, a map, or a metadata file, that can convey the information effectively and efficiently. The format should also follow some general principles, such as using plain language, avoiding jargon, providing examples, using headings and subheadings, using tables and figures, and citing references. The format should also comply with any relevant standards, guidelines, or conventions, such as the ISO 19115 metadata standard, the FGDC metadata content standard, or the OGC metadata profile.

5 Share the documentation

The fifth step in documenting GIS data limitations is to share the documentation with the data users and providers. This involves making the documentation accessible, discoverable, and understandable for the intended audience. The documentation can be shared through various channels, such as a web portal, a data catalog, a data repository, or a data package. The documentation should also be updated and maintained regularly, to reflect any changes or updates in the data, methods, or users. The documentation should also be reviewed and evaluated periodically, to ensure its quality, relevance, and usefulness.

6 Examples of documentation

The final step in documenting GIS data limitations is to look at examples of how other organizations or projects have documented their GIS data limitations. These examples can be used for inspiration, guidance, and best practices. For instance, the USGS National Map Accuracy Standards set out accuracy requirements and testing methods for topographic maps and digital geospatial data products. The EPA EnviroAtlas Data Limitations and Disclaimers explain the limitations and uncertainties of environmental data and indicators used in the EnviroAtlas web tool. ESRI Data Reviewer is another software tool that helps users document, manage, and report data quality issues and errors in GIS data sets.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?