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

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. 22 February 20102

ORNL DAAC Citation Policy 22 February    Citation is in the name of the investigators  Example (with DOI):  Turner, D.P., W.D.Ritts, and M. Gregory BigFoot NPP Surfaces for North and South American Sites, Data set. Available from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. [ doi: /ORNLDAAC/750

What Problem Are We Addressing? 22 February  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

What Is a DOI? 22 February  Technically, it’s a particular Handle implementation  Limited number of registrars  Each publisher gets a prefix (e.g )  Publisher assigns an 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   doi: /ORNLDAAC/945

ORNL Experience 22 February  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

Different types of update operations 22 February  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

DOIs work well for some things 22 February  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

DOI’s less appropriate for other things 22 February  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

Good citations help assess dependence 22 February  Synthesis is increasingly important science  Are all of the data used in the study independent?  Example: Luyssaert et al Net Primary Productivity (NPP)  Data at ORNL DAAC (doi: /ORNLDAAC/949)  Article at doi: /j 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?

Data Identifiers are evolving 22 February  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  See  Globally Unique Identifiers (GUIDs)  Need some type of resolution mechanism  Big challenge to support something “forever”

Impact Metrics 22 February  “Cited” means formal citation in reference list  “Referred” means the data was acknowledged somewhere in the body of the paper