Vocabulary Hosting: A Modest Proposal

Harry Halpin, <hhalpin@w3.org>

Lambda

Linked-AI 2010, Stanford, March 2010

The Problem: Choose a Vocabulary

Assume you want to choose a vocabulary (microformat, microdata, RDFa, standards) to mark up some structured data in HTML (or even some other format).

A user wants to use RDFa to mark up something as simple as some personal information attached to a review, how should they do it?

  1. FOAF: http://xmlns.com/foaf/spec/
  2. W3C RDF mappings of vCard: http://www.w3.org/TR/vcard-rdf
  3. Google's vocabulary: http://rdf.data-vocabulary.org

Too Many URIs!

There are too many URIs for the same thing...

An average of 1,339 URIs (S.D. 8,000) returned per query. That's a lot, but most may obviously be URIs that just mention the term...

return frequency

Top Entities and Concepts

Number of Searches (RDF Hits) Entity:
  1. 7311 (99) david blaine
  2. 2997 (134) jessica alba
  3. 2100 (16723) nick
  4. 1280 (178) michael hayden
  5. 1098 (10) marcus vick
  6. 1092 (199) keith urban
  7. 1015 (43) lane bryant
  8. 990 (55) desmond dekker
  9. 922 (312) jennifer white
  10. 900 (100) clay aiken
  11. 883 (359) bill cosby
    Concepts:
  1. 11383 (10767) weather
  2. 10321 (7777) dictionary
  3. 3675 (434333) people
  4. 3217 (189115) music
  5. 3117 (7196) monster
  6. 2192 (1444) autism
  7. 1468 (149436) map
  8. 1198 (17562) travel
  9. 1191 (12067) pregnancy
  10. 1104 (82074) news

The power-law blues

Very few empirical studies have been done on Linked Data, and often of the type "Look, it's a power-law!" without any proper statistical tests. See Clauset, Newman et al. paper referenced in my paper for a better method! correlation frequencies

Entity Queries: alpha = 2.31, with long tail behavior starting around a frequency of 17 and a Kolmogorov-Smirnov D-statistic of .0241, indicating a significant good fit.

Concept Queries: The alpha= of the queries for concept queries was calculated to be 2.12, with long tail behavior starting around a frequency of 36 with a Kolmogorov-Smirnov D-statistic of .017.

Hypertext Query Frequency and Linked Data?

Question: Is the amount of Linked Data returned correlated with the popularity of the query?

No: Spearman's rank correlation statistic was the insignificant .0077 (p > .05), while for concept queries, the correlation was the still insignificant at .0125 (p > .05)

correlation frequencies

Hypertext Query Frequency and Linked Data?

Question: Is the amount of Linked Data returned correlated with the popularity of the query?

No: Spearman's rank correlation statistic was the insignificant .0077 (p > .05), while for concept queries, the correlation was the still insignificant at .0125 (p > .05)

correlation frequencies

Vocabulary Hosting Efforts

  1. Schemaweb.info
  2. xmlns.org
  3. Ontaria
  4. Ontolingua

Vocabulary Hosting Requirements

Vocabulary Preservation

How can multiple vocabulary hosts be decentralized?

Linked Data Cloud as of 2007

Linked Data Cloud as of Now-ish (late 2009)

The Modest Proposal

Who will do this?

Any takers?