Knowing the spatial accuracy of geospatial data is an important first step in determining its suitability for your intended application. Unfortunately, this information is not an inherent characteristic of most geospatial data.

Metadata, commonly referred to as data about data, often accompanies digital geospatial data and includes information about who created the data, when it was created, what it contains, etc. This should be the first place to look for accuracy information. If metadata is missing, or if it exists but does not contain information on spatial accuracy, the next step might be to contact the organization or individual that provided the geospatial data and ask if they can provide information on the data's spatial accuracy. Again, contact information is also found in the metadata.

Should the request prove to be unsuccessful, it is ultimately your decision whether or not to trust these data for your application, and document this decision in the metadata for your own data products.