Data Management

Data Citation Frequently Asked Questions

Purpose of Frequently Asked Questions (FAQs)  

  • For USGS data users: Provide best practices for citing and accrediting referenced data.  

  • For USGS data providers: Offer guidance for generating and distributing recommended data citations of authored and distributed data. Data providers include data authors and data distributors. 

 

Context  

Frequently Asked Questions (FAQs) offer guidance and information based on the following data types: 

Non-USGS data products fall into these same categories; however, other organizations may define them differently. 

 

Supporting Terminology 

  • Author: “The people or organizations responsible for the intellectual work to develop a data [product]. The data creator.” (ESIP Data Preservation and Stewardship Committee, 2019) 

  • Granule: “The smallest aggregation of data that can be independently managed (described, inventoried, retrievable) [by the data provider]” (Doja, 2007) (e.g., a single data file within a collection of data files or a single dataset within a collection of datasets). 

  • Subset: A portion of a data product that a user retrieves through a set of queried parameters. A subset may contain data from multiple granules within a data product (e.g., all data points within a data product that fall within a geographic or temporal range) or a portion of a data product that only includes some of the available parameters (e.g., location and peak hydrologic flow).   

  • Landing page: A web page that provides access to the data and metadata for a data product. 

  • Digital Object Identifier (DOI): A persistent identifier used to identify content objects uniquely and to link to them on the web. DOIs are standardized by the International Organization for Standardization (ISO 26324). If a web link changes, the information stored with a DOI can change programmatically while the DOI remains persistent. 
     

Background 

The Open, Public, Electronic, and Necessary (OPEN) Government Data Act requires federal agencies to publish data products in open, machine-readable formats that are available at “no cost to the public and with no restrictions on copying, publishing, distributing, transmitting, citing, or adapting.” The USGS Survey Manual chap. 502.8 further requires that USGS data products be assigned a DOI and be accompanied by a recommended citation. The USGS Survey Manual chap. 502.8 also states that “all USGS scientific publications must reference their associated data.” These frequently asked questions and answers are intended to help USGS personnel comply with these policies and make USGS research more transparent and trustworthy. 

 

FAQ Table of Contents 

1. General FAQs 

     1.1 What is a data citation? 

     1.2 Why use data citations? 

     1.3 What elements should be included in a data citation? 

     1.4 What does a data citation look like? 

2. FAQs for Data Users 

     2.1 What data products should I cite in a published product, such as a journal article or research paper? 

     2.2 When should I maintain a copy of data that I cite? 

     2.3 How should I cite a data product when the recommended citation is for a published article instead of the data? 

     2.4 How should I cite a data product that does not include a recommended citation? 

3. FAQs for Data Providers 

     3.1 What information do USGS data providers need to offer to users about data citation? 

     3.2 How should USGS data providers set up data products that will grow or change through time so that users can cite them? 

     3.3 What other citation factors should I consider when assigning DOIs for my data? 

     3.4 Who should you include in the author element for a data product? 

     3.5 Is it appropriate for authors listed in a data citation to change over time? 

 

1. General FAQs 

 

1.1 What is a data citation? 

Goal: Introduce data users and providers to the concept of data citation. 

Answer: Data citation is the practice of referencing data products used in research. A data citation includes key descriptive information about the data product, such as the title, source, and responsible parties. See FAQ 1.3 for additional information about the citation elements. 

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1.2 Why use data citations? 

Goal: Highlight the importance and purpose of data citations and why these are necessary for scientific integrity and reproducibility.  

Answer: The goal of data citation is to provide scientific transparency and attribution. Data citations benefit the researcher, funding organization, data repositories, scientific community, and general public. Data citations serve many purposes: 

  • To aid scientific trustworthiness and reproducibility through direct, unambiguous connection to the precise data used; 

  • To provide fair credit for data creators or authors, data stewards, and other entities in the data production and curation process; 

  • To ensure scientific transparency and reasonable accountability for data authors and stewards; 

  • To aid in tracking the impact of a dataset and the associated repository through reference in scientific literature; 

  • To help data authors verify how their data are being used; 

  • To help future users identify how others have used the data. (ESIP Data Preservation and Stewardship Committee, 2019) 

Please note that while data citations aid scientific reproducibility, it is rarely possible to achieve full reproducibility with a data citation alone. Additional information about data processing is necessary in the form of metadata and executable workflows or analytical pipelines (reference “Workflow Capture,” USGS Data Management Website). 

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1.3 What elements should be included in a data citation? 

Goal: Document the elements that should appear in a data citation. 

Answer: The elements in Table 1 show the typical information provided in a data citation. Data providers should include as many available citation elements from Table 1 as possible to support the purposes listed in FAQ 1.2. Data users should use the most complete data citation available.  

  • ‘R’ indicates that the element is recommended and should be used if available.  

  • ‘O’ indicates that the element is optional to include in the data citation. See footnotes for additional information about when it is appropriate to use optional elements. 

Table 1. Elements of a data citation
Element Static Versioned Dynamic
Author R R R
Publication year R R R
Title R R R
Version ID   R note 1
Publisher R R R
Access date note 2 R R R
Digital Object Identifier (DOI) note 3 R R R
Query parameters note 4 O O O
Direct access link note 5 O O O

note 1 Data providers may version dynamic data products in situations where there are major changes across all data. For example, if the data provider reprocesses data with an improved algorithm (ESIP Data Preservation and Stewardship Committee, 2019). 

note 2 If a data provider is releasing data alongside a journal article or other published research, the data citation for that data product does not require an access date in that publication. The recommended citation on a data product’s landing page should not have an access date. The access date is included by data users when they cite the data product. 

note 3 If a DOI is not available, provide a direct access link (see note 4 below). 

note 4 Query parameters describe a subset of a data product in plain text. Documenting query parameters helps to support provenance and transparency by enabling others to 1) understand what subset was used, and 2) potentially recreate the same subset of data that was used in research.  

  • Include query parameters in a data citation when the query parameter string is short and simple to document.  

  • If the query parameter string is too long to include in the data citation, describe the query elsewhere in the manuscript or product documentation.  
         - Data users should use their best judgement or guidelines from publishers on what is considered ‘too long.’  

note 5 Direct access links are URLs that bring users to the specific data used in research. Direct access links should be used with caution because they are not persistent and can break over time as data systems and technology change. There are three scenarios where a direct access link could be used within a data citation: 

  • When a data product does not have a DOI or other persistent identifier, the direct access link can provide access to the data for users in the short term. Retain a copy of those data internally for scientific integrity and reproducibility according to records management policies (see FAQ 2.2). 

  • When a static data product has a DOI but the granule used does not have a DOI or other persistent identifier, the granule can be cited like a chapter within a book. This citation approach would include the DOI for the static data product and can optionally include a direct access link to the granule. Check with the journal where you will publish to see if inclusion of the direct access link is appropriate. 

  • When a subset of a dynamic data product is used and a persistent identifier is not available for the subset, it is most appropriate to use query parameters to document the subset. Query parameters are important to document in addition to direct access links because direct access links are not persistent. In certain circumstances, direct access links can also be used. Check with the journal where you will publish to see if inclusion of the direct access link is appropriate.

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1.4 What does a data citation look like? 

Goal: Provide an example of a data citation using the USGS citation style. 

Answer: Different citation styles exist for accommodating varying disciplines, but the content of elements included in a data citation are mostly standardized. Below are examples of data citations using the USGS citation style.  

Static 

Full Data Product

van Manen, F.T., Smith, D.W., Haroldson, M.A., Stahler, D.R., Almberg, E.S., Whitman, C.L., and Cross, P.C., 2018, Canine distemper virus antibody titer results for grizzly bears and wolves in the greater Yellowstone ecosystem 1984–2014: U.S. Geological Survey data release, accessed January 2, 2020, at https://doi.org/10.5066/P96E4UCK

Granule of a Static Data Product

Sherwood, C.R., Brosnahan, S.M., Ackerman, S.D., Borden, J., Montgomery, E.T., Pendleton, E.A., and Sturdivant, E.J., 2018, Charles Point digital elevation model (DEM) from low-altitude aerial imagery from unmanned aerial systems (UAS) flights over of the Lake Ontario shoreline in the vicinity of Sodus Bay, New York in July 2017 (32-bit floating point GeoTIFF image), in Aerial imagery and photogrammetric products from unmanned aerial systems (UAS) flights over the Lake Ontario shoreline at Sodus Bay, New York, July 12 to 14, 2017: U.S. Geological Survey data release, accessed February 26, 2020, at https://doi.org/10.5066/P9XQYCD0. [Data directly accessible at https://www.sciencebase.gov/catalog/item/5b1ede6ce4b092d965254a3f.] 

Versioned 

Abdollahian, N., Jones, J.L., Ball, J.L., Wood, N.J., and Mangan, M.T., 2018, Data release for results of societal exposure to California's volcanic hazards (ver. 3.0, November 2019): U.S. Geological Survey data release, accessed February 10, 2020, at https://doi.org/10.5066/F7W66JRH

Dynamic 

Full Data Product

U.S. Geological Survey, 2020, BioData—Aquatic bioassessment data for the Nation: U.S. Geological Survey database, accessed February 20, 2020, at https://doi.org/10.5066/F77W698B

Subset of a Dynamic Data Product

U.S. Geological Survey, 2020, USGS 01646500 Potomac River near Wash, DC Little Falls Pump Sta, in USGS water data for the nation: U.S. Geological Survey National Water Information System database, accessed January 2, 2020, at https://doi.org/10.5066/F7P55KJN. [Query parameters: Format = WaterML 2.0; Site number = 01646500; Date range = 2011-10-01 to 2019-09-30; Site status = All. Data directly accessible at https://waterservices.usgs.gov/nwis/dv/?format=waterml,2.0&sites=01646500&startDT=2011-10-01&endDT=2019-09-30&siteStatus=all.

Hall, D.K., and G. A. Riggs, 2016, MODIS/Terra snow cover daily L3 global 500m grid (ver. 6.0): National Snow and Ice Data Center Data Set MOD10A1, accessed February 2, 2019, at https://doi.org/10.5067/MODIS/MOD10A1.006. [Query parameters: Oct. 2007- Sep. 2008, 84°N, 75°W; 44°N, 10°W] 

Ocean Networks Canada Society, 2019, Barkley Canyon upper slope fluorometer turbidity deployed 2019-05-16: Ocean Networks Canada Society dataset, accessed April 13, 2020, at https://doi.org/10.34943/fa04d675-3df2-4dc3-810b-cb365f7ec492. [Subset Query: 8297991] 

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2. FAQs for Data Users 

 

2.1 What data products should I cite in a published product, such as a journal article or research paper? 

Goal: Data citation is a new concept for many authors. The goal of this FAQ is to help authors understand what data they should cite in their published research. 

Answer: Cite the following data products: 

  • Data products that you use as inputs for your analyses, including data products released with the published research  

  • Data products that enable the production of new derivative data products  

  • Data products that you reference for comparison or clarity.  

If you used it, cite it, including your own data product. 

If the data used in the development of a publication are non-USGS data and are not publicly available, you should still cite them in the paper and a describe how the public can access the data (e.g. who to contact).  

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2.2 When should I maintain a copy of data that I cite but did not create? 

Goal: Let people know when it is important to maintain their own copy of someone else’s data that they used in their work. 

Answer:   

You must maintain a copy of another data provider’s data products used in the development of scientific conclusions if  

  • The data product is not published in a repository that guarantees long-term access to the data (This should only apply to non-USGS data. All USGS data should be in digital repositories approved by the USGS per Survey Manual chap. 502.9),  

  • The data product is dynamic and does not have a built-in audit capability that enables end users to understand what changed over time.  

Your copy does not need to be publicly accessible, but it must be retained for the length required by the USGS records schedule. You should store it alongside other records associated with your project. However, in cases where transparency and reproducibility are essential, you may choose to release the copy of the data alongside your other research outputs as a novel data product. Most often, the final data product would be the associated USGS data release for a publication. Before including the original data in a new data release, ensure that they are not considered to be controlled unclassified information such as copyrighted, proprietary, or under other restriction. Additionally, maintain any licenses associated with the original data in the new release according to the original data's instructions. 

Provide a new publication date, an updated author list, and a distinct title in the metadata for your released copy of the data, as well as a description of the creation of the subset and any modifications made. Credit original authors in the form of a data citation in the data release and the associated publication. 

See Survey Manual chap. 431.1 for more information on Federal records management. 

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2.3 How should I cite a data product when the recommended citation is for a published article instead of the data? 

Goal: Help data users understand how to cite non-USGS data products that recommend citing the associated published article instead of providing a recommended citation for the data product itself. 

Answer: It is common for data providers outside the USGS to use a citation for a published article as the recommended citation for their data product. This type of recommendation generally happens because many organizations weigh publication citations higher than data citations for promotion and tenure. The challenge with this citation approach is that published articles do not change over time, whereas data products can change. To ensure transparency of your research, you should cite the published article AND create and include a citation for the data based on information in FAQ 2.4. If an author has embedded the data in the publication as tables or supplemental information and they are not available as a standalone product, citing the publication is sufficient. 

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2.4 How should I cite a data product that does not include a recommended citation? 

Goal: Help data users understand how to cite a data product if a recommended citation is not provided by the data producer. 

Answer: Using the data citation elements referenced in Table 1, build a citation with all available elements referenced in the metadata, data, and website. See Table 2 for what information to provide for each data citation element.

Table 2. Explanation for finding data citation elements to build a citation
Data Citation Element Explanation
Author Use the name of the organization that produced the data product, if individual authors are unknown (e.g., "U.S. Geological Survey"). If a multiagency entity produced the data product (e.g., Imagery for the Nation or National Water Quality Monitoring Council), the author should be the name of the entity.
Publication year
  • Use the "last updated year" if the public release year is unknown. 

  • Use the year that you accessed the data as an extrapolated date if the "last updated year" is unknown. 

Title Use the name of data product or the name of a specific subset, if available. If you use the title of a subset, also include the title of the data product so the user has some frame of reference for the subset. See FAQ 1.4 for an example using the USGS citation style. 
Version ID and date of version publication (as applicable)
  • If the data product has a specific version ID, include it in the citation.  

  • For dynamic data products, if a "last updated date" is available, include this information in the version ID element with or without a version number. 

Publisher
  • Use the name of the organization publishing the data product. 

  • USGS data products will all use ”U.S. Geological Survey” as the publisher. The publisher element for USGS data products will also include the type of product (e.g., “data release,” “Data Series,” “database,” etc.). The publisher element can include the name of the database if you use the subset title earlier in the citation (e.g., “U.S. Geological Survey National Water Information System”). 

Date that you accessed the data If the data in the data product are time-stamped, include the time you accessed it in the citation. This will allow users to filter out data added after this date and time. Time is important to include if data are changing continuously. 
Digital Object Identifier Include the DOI for the data product. If a DOI does not exist, include the direct access link where others can access the data product and retain a copy of those data internally for scientific integrity and reproducibility according to records management policies (see FAQ 2.2). 
Query parameters used to access the data
  • Provide information about the data structure to enable others to rebuild your query using the same parameters. Example parameters may include bounding coordinates, date range, temperature, salinity, site numbers, data format.  

  • If query parameters are too long to include in the citation, provide this information elsewhere in the manuscript or product documentation.  

  • Example query parameters for the NWIS database following USGS citation style: [For query parameters, use Format = WaterML 2.0; Site number = 01646500; Date range = 2011-10-01 to 2019-09-30; Site status = All]

Direct access link (if available) Direct access links should be used with caution because they are not persistent and can break over time as data systems and technology change. There are three scenarios where a direct access link could be used within a data citation: 
  • When a data product does not have a DOI or other persistent identifier, the direct access link can provide access to the data for users in the short term. Retain a copy of those data internally for scientific integrity and reproducibility according to records management policies (see FAQ 2.2). 

  • When a static data product has a DOI but the granule used does not have a DOI or other persistent identifier, the granule can be cited like a chapter within a book. This citation approach would include the DOI for the static data product and can optionally include a direct access link to the granule. Check with the journal where you will publish to see if inclusion of the direct access link is appropriate. 

  • When a subset of a dynamic data product is used and a persistent identifier is not available for the subset, it is most appropriate to use query parameters to document the subset. Query parameters are important to document in addition to direct access links because direct access links are not persistent. In certain circumstances, direct access links can also be used. Check with the journal where you will publish to see if inclusion of the direct access link is appropriate. 

Examples:

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3. FAQs for Data Providers 

 

3.1 What information do USGS data providers need to offer to users about data citation? 

Goal: Help data providers understand their responsibilities for data citation. 

Answer:  

Static 

Include a recommended citation on the landing page for the data product. The citation should include the elements noted in FAQ 1.3.  

Versioned 

Include a recommended citation on the landing page for the data product. The citation should include the elements noted in FAQ 1.3. Additionally, data providers should include version history documentation describing the changes in each version of the data product (see OSQI Guidance on Documenting Revisions to USGS Scientific Digital Data Releases for USGS data products and USGS Publishing Standards Memorandum 2013.05 for data in USGS publication series [data series, primarily]).  Also, include information about how to retrieve previous versions of the data product.  

Dynamic 

Include a recommended citation on the landing page for the data product. The citation should include the elements noted in FAQ 1.3. Additionally, data providers should be transparent about how frequently their data change. For example, data providers should provide information on how users will be able to get back to an exact version of the data requested in the future. This information will help users determine if they need to maintain a copy of the data that they use in a publication for records management purposes. 

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3.2 How should USGS data providers set up data products that will grow or change through time so that users can cite them? 

Goal: Help data providers plan for updates to a data product prior to the initial release. 

Answer: Data providers will have different considerations depending on how they plan to release the data. Specifically, will they release the data as a series of static data products, a versioned data product, or a dynamic data product?  

Static 

There are no special considerations for data products released as a series of static data products. Each data product will have its own DOI and citation. Different repositories may have the capacity to organize a collection of related data products. Even so, the citation will still occur at the individual data product level. 

Versioned 

If possible, structure versioned data products so that users can understand which data are available in each version. If a user includes the version ID in a data citation, subsequent users should understand which data are being referenced. Include fields in the data for tracking when an author adds a data value. This information can be valuable to data managers and downstream data users needing to query the data. It is a best practice to account for these considerations at the start of a project to inform data management protocols and file structure.  

Choose a title that is descriptive of the data but that will not need to change when an author adds new data. For example, if the data will change temporally, do not include a date range in the title. A stable title will help to ensure a persistent citation even as the version ID changes. 

See FAQs below to help determine who to include in the author element of a citation to a data product that will change with time. 

  • Who should you include in the author element for a data product? (FAQ 3.4

  • Is it appropriate for authors listed in a data citation to change over time? (FAQ 3.5

Dynamic 

Structure dynamic data products so that users can understand when the author added or modified the data. If a user includes their access date in a data citation, subsequent users should understand which data are being referenced. Consider using point-in-time architecture to allow users to query the data product to see what it looked like at any given time (Fuller, 2007). This strategy can be helpful when modifications and deletions of data will be common and not easy to track in the data product (table 3).

Table 3. Example data table with columns tracking date updated or deleted and the original ID
id data_value date_added date_updated date_deleted original_id
1234 12 2016-01-01 2017-01-01    
1357 14 2016-01-01   2017-01-01  
2345 24 2017-01-01 2018-01-01   1234
2468 18 2017-01-01      
3456 10 2018-01-01     1234

Choose a title that is descriptive of the data but that will not need to change when an author adds new data. For example, if the data will change temporally, do not include a date range in the title. A stable title will help to ensure a persistent citation even as the data change overtime. 

See FAQs below to help determine who to include in the author element of a citation to a data product that will change with time. 

  •  Who should you include in the author element for a data product? (FAQ 3.4

  • Is it appropriate for authors listed in a data citation to change over time? (FAQ 3.5

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3.3 What other citation factors should I consider when assigning DOIs for my data? 

Goal: Help data providers understand when to assign granular DOIs in addition to a top-level DOI. 

Answer:  

There are different factors to consider when deciding how many DOIs to assign for your data:  

  •  What level of granularity is necessary for data citation to enable transparency and reuse?  

    Packaging data that will often be used together as a single data product with one DOI will simplify data citation from the end user’s perspective. If individual granules will likely be used separately, assigning DOIs for each granule will enable more transparency in the citation.   

  • How do you want to track the impact or use of the data? 
     
    One way to track impact of data is by counting the number of times the data’s DOI appears as a reference in publications. If you would like to track downstream use of data at a particular granularity, assign DOIs and create recommended citations at that level. A data product can have a top-level, collection DOI assigned and individual DOIs for each of its granules or subsets. 

  • How will you manage the data citations over time? 

    If you intend to version data granules independently over time, each granule can have its own DOI and recommended citation. These separate citations will allow you to be very clear with users about what has changed. If you intend to version data granules together or will not have any planned updates, a single DOI will likely be enough. 

There are other factors beyond data citation, such as discovery and access, that you should consider when structuring, packaging, and reserving DOIs for your data. For more information, see the Structuring and Documenting a USGS Public Data Release training module on the USGS Data Management Website. 

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3.4 Who should you include in the author element for a data product? 

Goal: Help data providers determine who should be included in the author list for a data product. 

Answer

Static

Include individuals who contribute to the intellectual work of a static data product in the author element. If a static data product has many contributors, consider using an organizational author in the citation. Include individuals and organizations in the metadata for the data and the DOI. Inclusion of individuals in the metadata will provide credit and responsibility for their work on the data. Inclusion of individuals in the DOI will allow the product to appear on their USGS staff profiles and ORCID profiles. 

Versioned 

Use organizational authors in the author element for versioned data products, if authors may change over time. Use an organizational unit that is unlikely to change with restructuring or name changes. USGS science center names change often and are usually not appropriate for use in data citations for versioned data products. The best top-level attribution would be “U.S. Geological Survey.” Include individuals and organizations in the metadata for the data and the digital object identifier (DOI).  Inclusion of individuals in the metadata will provide credit and responsibility for their work on the data. Inclusion of individuals in the DOI will allow the product to appear on their USGS staff profiles and ORCID profiles. Include the recommended citation in the metadata using the organizational author. Also, provide a description of the individual authors who contributed to each version. 

Dynamic 

Same as Versioned Data 

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3.5 Is it appropriate for authors listed in a data citation to change over time? 

Goal: To help data providers understand whether they can update the author element in a citation if authors change over time. 

Answer: It is generally not appropriate for the author element in a data citation to change. Such changes can cause confusion in determining whether two citations are referring to the same data product. If you release a data product with the intention to update it over time, see FAQ 3.4 for guidance on planning for changes in authorship. If you do not intend to update a data product over time, but an additional author contributes to an unplanned revision after release, update the author element to include the additional author. Include documentation for the data product (e.g., in the metadata, DOI, and revision history) describing which authors contributed to which version. 

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References 

Doja, M.N., 2007, International encyclopaedia of engineering and technology: Mittal Publications, p. 636. 

ESIP Data Preservation and Stewardship Committee, 2019, Data citation guidelines for earth science data, version 2: Earth Science Information Partners web page, accessed April 22, 2020, at https://doi.org/10.6084/m9.figshare.8441816

Fuller, A., 2007, Database design—A point in time architecture: Red Gate Software Ltd. web page, accessed March 6, 2020, at https://www.red-gate.com/simple-talk/sql/database-administration/database-design-a-point-in-time-architecture/.