ORNL DAAC Experience With Digital Object Identifiers ( DOIs )

1. ORNL DAAC Experience With Digital Object Identifiers (DOIs) Bruce Wilson, ORNL DAAC Managerfor NASA Data Center Managers telecon 22 Feb 2010

2. Acknowledgements and Sources • Bob Cook, ORNL DAAC Scientist • DataONE Core CI team, particularly Matt Jones (UCSB) and Dave Vieglais (U Kansas) • ESIP Product & Stewardship, particularly Ruth Duerr (NSIDC) and Bob Downs (SEDAC) • Note: ORNL’s CDIAC has started assigning DOI’s for all of their finalized data sets.

3. ORNL DAAC Citation Policy • http://daac.ornl.gov/citation_policy.html • http://daac.ornl.gov/citation_style.html • Citation is in the name of the investigators • Example (with DOI): • Turner, D.P., W.D.Ritts, and M. Gregory. 2006. BigFoot NPP Surfaces for North and South American Sites, 200-2004. Data set. Available from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. [http://daac.ornl.gov]. doi:10.3334/ORNLDAAC/750

4. What Problem Are We Addressing? • ORNL DAAC has used data citations for many years • Track use of data in literature (impact) • Provide credit to investigators • Create incentives for publishing and sharing data • Some journal editors rejected URL citations • Regarded as transient (very valid concern) • Some scientists didn’t see data as “publication” • We want data sets listed on CV’s • Strong way to measure impact of data set for tenure

5. What Is a DOI? • Technically, it’s a particular Handle implementation • Limited number of registrars • Each publisher gets a prefix (e.g. 10.3334) • Publisher assignsan identifier after the prefix • Publisher registers the DOI with a URL and metadata • Endpoint URL can be updated as systems evolve • Registration can include back-links (documents cited) • Enables citation chain • Can help establish dependence of data sets (future use) • DOI resolves at use time to current endpoint URL • http://dx.doi.org/10.3334/ORNLDAAC/945 • doi:10.3334/ORNLDAAC/945

6. ORNL Experience • Working with CrossRef as a registrar • $500/year membership fee, ~$250 to register 900 DOIs • Our DOIs resolve to a web page about the dataset • Very positive reaction from investigators • Makes usage metrics somewhat easier • Haven’t implemented backlinking yet, but should • It’s a social contract that we don’t change the data • Updated dataset ==> new DOI (if “significant”) • Minor updates (spelling corrections, clarifications) OK • Adding a new data format file is harder to decide

7. Different types of update operations • Correct reference or spelling in documentation • No change in DOI, but still should show provenance • Augment documentation for clarity • No change in DOI, but still should show provenance • Add copy of data in new format • Probably no change in DOI, but still should show provenance • Correct error in data • New DOI; show provenance • Append new data • New DOI; show provenance

8. DOIs work well for some things • Finalized datasets (ones that don’t change) • Datasets that change occasionally • Global Fire emission dataset updated annually • Documents (best practices, product documentation) • Could work for Remote Sensing at the product level

9. DOI’s lessappropriate for other things • Cost (primarily) prohibits assigning for granules • Unique ID’s needed, but may be data center-internal • DOIs are a publishing standard, adapting for data ID • Dynamically generated and stream data • One DOI per MODIS product probably makes sense • Desirable to be able to reproduce data, but hard • MODIS subsetter (particularly considering reprocessed granules) • Would have to have a separate identifier for each request • Other processing tools, like OGC web services • Possibly use data citations with workflow provenance • Partition data citation from data reproducibility

10. Good citations help assess dependence • Synthesis is increasingly important science • Are all of the data used in the study independent? • Example: Luyssaertet al Net Primary Productivity (NPP) • Data at ORNL DAAC (doi:10.3334/ORNLDAAC/949) • Article at doi:10.1111/j.1365-2486.2007.01439.x • Drawn from many sources (very well documented) • ftp://ftp.daac.ornl.gov/data/global_vegetation/forest_carbon_flux/comp/appendix_a_database_sources.pdf • Future work using Luyssaert dataset can’t compare it to any of the underlying data • Also an issue in cal-val for remote sensing • What data was used for this RS product?

11. Data Identifiers are evolving • DataCite.org (German Library + others, including CDL) • Particularly focused on research data • Life Science Identifiers (LSID) • Heavily used in oceans community • Some concerns about URN versus URI • Seehttp://en.wikipedia.org/wiki/LSID • Globally Unique Identifiers (GUIDs) • Need some type of resolution mechanism • Big challenge to support something “forever”

12. Impact Metrics • “Cited” means formal citation in reference list • “Referred” means the data was acknowledged somewhere in the body of the paper