Heuristics for Fixing Common Errors
in Deployed schema.org Microdata
Robert Meusel and Heiko Paulheim
2
Motivation
Heuristics for Fixing Common Errors in Deployed schema.org Microdata - Meusel and Paulheim - ESWC 2015
3
Microdata in a Nutshell
 Adding structured information to web pages
• By marking up contents and entities
 Arbitrary v...
4
Schema.org in a Nutshell
 Vocabulary for marking up entities on web pages
• 675 classes and 965 properties (as of May 2...
5
Schema.org in a Nutshell – Coverage
 Schema.org has incorporated some popular vocabularies, like:
• Good Relations (201...
6
Microdata with Schema.org in HTML Pages
<html>
…
<body>
…
<div id="main-section" class="performance left" data-
sku="M17...
7
So Far, So Good …
 Schema is well explained on the schema.org websites
 Data providers are supported by validation too...
8
So What Could Possibly Go Wrong?
 Usage of wrong namespaces
• http./schema.org
 Usage of undefined types
• http://sche...
9
Compiling a Schema.org Dataset
 Starting point: all pages in the CommonCrawl that contain
Microdata
 What could be (me...
10
Namespace Violations
 More than 98% of the preselected pages use a correct
namespace
 Frequent namespace variations:
...
11
Undefined Types
 Used by around 6% of all data providers
 Typical causes:
• Misspellings: http://schema.org/Stores
• ...
12
Undefined Properties
 Used by around 4% of all data providers
 Typical Causes:
• Miscapitalization: http://schema.org...
13
Confusion of Object Properties with Data Properties
 i.e. using an object property with a string values
 Used by over...
14
Confusion of Data Properties with Object Properties
 i.e. using a data property with a complex object
 Used by less t...
15
Property Domain Violations
 i.e. using a property with a subject not included in its domain
 Used by 4% of all data p...
16
Data Property Range Violations
 i.e. using a data property with an incompatible literal
 Used by 9.6% of all data pro...
17
Object Property Range Violations
 i.e. using an object property with a type outside its range
 Used by 8.6% of all da...
18
Schema.org Compliance Summary
 Surprisingly high level of compliance
 Providers are often not technology evangelists ...
19
Identifying and Fixing Wrong Namespaces
 Main errors due to missing slashes, wrong protocol and
capitalization
 Simpl...
20
Handling Undefined Types and Properties
 Main errors due to wrong capitalization
 Heuristic: Ignore capitalization wh...
21
Handling Object Properties with Literal Values
 Main objects modeled as literals are s:Organization,
s:Person and s:Po...
22
Handling Property Domain Violations
 Main cause are shortcuts
 Heuristic to find the
property R and type T
for a doma...
23
Heuristics Summary
 Over 410 million wrong triples could be corrected
 Over 700 million missing triples could be adde...
24
LD4IE Challenge @ ISWC 2015
Heuristics for Fixing Common Errors in Deployed schema.org Microdata - Meusel and Paulheim ...
25
Thank you! Questions? Feedback?
Data and more insights can be found at:
http://webdatacommons.org/structureddata/2013-
...
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Heuristics for Fixing Common Errors in Deployed schema.org Microdata

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Being promoted by major search engines such as Google,
Yahoo!, Bing, and Yandex, Microdata embedded in web pages, especially using schema.org, has become one of the most important markup languages for the Web. However, deployed Microdata is most often not free from errors, which limits its practical use. In this paper, we use
the WebDataCommons corpus of Microdata extracted from more than 250 million web pages for a quantitative analysis of common mistakes in Microdata provision. Since it is unrealistic that data providers will provide clean and correct data, we discuss a set of heuristics that can be applied on the data consumer side to fix many of those mistakes in a
post-processing step. We apply those heuristics to provide an improved knowledge base constructed from the raw Microdata extraction.

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Heuristics for Fixing Common Errors in Deployed schema.org Microdata

  1. 1. Heuristics for Fixing Common Errors in Deployed schema.org Microdata Robert Meusel and Heiko Paulheim
  2. 2. 2 Motivation Heuristics for Fixing Common Errors in Deployed schema.org Microdata - Meusel and Paulheim - ESWC 2015
  3. 3. 3 Microdata in a Nutshell  Adding structured information to web pages • By marking up contents and entities  Arbitrary vocabularies are possible • Practically, only schema.org is deployed on a large scale • Plus its historical predecessor: data-vocabulary.org  Similar to RDFa Heuristics for Fixing Common Errors in Deployed schema.org Microdata - Meusel and Paulheim - ESWC 2015 <div itemscope itemtype="http://schema.org/PostalAddress"> <span itemprop="name">Data and Web Science Group</span> <span itemprop="addressLocality">Mannheim</span>, <span itemprop="postalCode">68131</span> <span itemprop="addressCountry">Germany</span> </div>
  4. 4. 4 Schema.org in a Nutshell  Vocabulary for marking up entities on web pages • 675 classes and 965 properties (as of May 2015, release 2.0)  Promoted and consumes by major search engine companies • Google, Bing, Yahoo!, and Yandex • Google Rich Snippets  Community-driven evolution and development  Can be used with Microdata and RDFa • Hardly used together with RDFa (<0.1% of RDFa-using websites [1]) Heuristics for Fixing Common Errors in Deployed schema.org Microdata - Meusel and Paulheim - ESWC 2015 [1] http://webdatacommons.org/structureddata/2014-12/stats/stats.html
  5. 5. 5 Schema.org in a Nutshell – Coverage  Schema.org has incorporated some popular vocabularies, like: • Good Relations (2012) • W3C BibExtend (2014) • MusicBrainz vocabulary (2015) • Automotive Ontology (2015) Heuristics for Fixing Common Errors in Deployed schema.org Microdata - Meusel and Paulheim - ESWC 2015
  6. 6. 6 Microdata with Schema.org in HTML Pages <html> … <body> … <div id="main-section" class="performance left" data- sku="M17242_580“> <h1> Predator Instinct FG Fußballschuh </h1> <div> <meta content="EUR"> <span data-sale-price="219.95">219,95</span> … </body> </html> HTML pages embed directly markup languages to annotate items using different vocabularies <html> … <body> … <div id="main-section" class="performance left" data- sku="M17242_580" itemscope itemtype="http://schema.org/Product"> <h1 itemprop="name"> Predator Instinct FG Fußballschuh </h1> <div itemscope itemtype="http://schema.org/Offer" itemprop="offers"> <meta itemprop="priceCurrency" content="EUR"> <span itemprop="price" data-sale- price="219.95">219,95</span> … </body> </html> 1._:node1 <http://www.w3.org/1999/02/22-rdf-syntax- ns#type> <http://schema.org/Product> . 2._:node1 <http://schema.org/Product/name> "Predator Instinct FG Fußballschuh"@de . 3._:node1 <http://www.w3.org/1999/02/22-rdf-syntax- ns#type> <http://schema.org/Offer> . 4._:node1 <http://schema.org/Offer/price> "219,95"@de . 5._:node1 <http://schema.org/Offer/priceCurrency> "EUR" . 6.… Heuristics for Fixing Common Errors in Deployed schema.org Microdata - Meusel and Paulheim - ESWC 2015
  7. 7. 7 So Far, So Good …  Schema is well explained on the schema.org websites  Data providers are supported by validation tools (e.g. Yandex structured data validator) when deploying  Win-Win for both sides  Plus: Data is (mostly) free accessible in the Web …. but:  >100.000s of data providers, which are mostly no schema.org experts or evangelists  Validators & schema might help but there is no need to use them Heuristics for Fixing Common Errors in Deployed schema.org Microdata - Meusel and Paulheim - ESWC 2015
  8. 8. 8 So What Could Possibly Go Wrong?  Usage of wrong namespaces • http./schema.org  Usage of undefined types • http://schema.org/Breadcrumb  Usage of undefined properties • http://schema.org/postID  Confusion of datatype properties and object properties • _:n1 s:address “Jump Street 21”  Property domain and range violations • _:n1 a s:Product _:n1 s:price “for free” Heuristics for Fixing Common Errors in Deployed schema.org Microdata - Meusel and Paulheim - ESWC 2015
  9. 9. 9 Compiling a Schema.org Dataset  Starting point: all pages in the CommonCrawl that contain Microdata  What could be (meant to be) schema.org? • Everything that contains “schema.org” as substring in a namespace • Everything that contains URIs where the protocol and authority is similar to “http://schema.org/” (with an EditDistance of 1) • Filter noise: removing all namespaces that occur only on one website Heuristics for Fixing Common Errors in Deployed schema.org Microdata - Meusel and Paulheim - ESWC 2015 Final corpus consists of: 6.4 billion triples extracted from over 217 billion pages belonging to 398,542 data providers which is 86% of all Microdata in the corpus.
  10. 10. 10 Namespace Violations  More than 98% of the preselected pages use a correct namespace  Frequent namespace variations: • http://www.schema.org/ • https://schema.org • http:/schema.org • http://SChema.org Heuristics for Fixing Common Errors in Deployed schema.org Microdata - Meusel and Paulheim - ESWC 2015 Debated!
  11. 11. 11 Undefined Types  Used by around 6% of all data providers  Typical causes: • Misspellings: http://schema.org/Stores • Miscapitalization: http://schema.org/localbusiness  Comparison to LOD Compliance • 5.8% of all Microdata documents • 38.8% of all LOD documents (Hogan et al., 2010) Heuristics for Fixing Common Errors in Deployed schema.org Microdata - Meusel and Paulheim - ESWC 2015 …/Store …/LocalBusiness
  12. 12. 12 Undefined Properties  Used by around 4% of all data providers  Typical Causes: • Miscapitalization: http://schema.org/contentURL • Close but miss: http://schema.org/currency http://schema.org/fax • Made up: http://schema.org/blogId http://schema.org/postId  Comparison to LOD Compliance • 9.7% of all Microdata documents • 72.4% of all LOD documents (Hogan et al., 2010) Heuristics for Fixing Common Errors in Deployed schema.org Microdata - Meusel and Paulheim - ESWC 2015 …/contentUrl …/priceCurrency
  13. 13. 13 Confusion of Object Properties with Data Properties  i.e. using an object property with a string values  Used by over 56.6% of all data providers  Typical properties: • http://schema.org/addresscountry • http://schema.org/manufacturer • http://schema.org/author • http://schema.org/brand  Comparison to LOD Compliance • 24.35% of all Microdata documents • 8% of all LOD documents (Hogan et al., 2010) Heuristics for Fixing Common Errors in Deployed schema.org Microdata - Meusel and Paulheim - ESWC 2015
  14. 14. 14 Confusion of Data Properties with Object Properties  i.e. using a data property with a complex object  Used by less than 0.2% of all data providers  Comparison to LOD Compliance • 0.6% of all Microdata documents • 2.2% of all LOD documents (Hogan et al., 2010) Heuristics for Fixing Common Errors in Deployed schema.org Microdata - Meusel and Paulheim - ESWC 2015
  15. 15. 15 Property Domain Violations  i.e. using a property with a subject not included in its domain  Used by 4% of all data providers  Typical violations are mainly shortcuts • s:price used on s:Product • s:streetAddress used on s:LocalBusiness  Comparison to LOD Compliance: • Difficult to compare as semantics are different • List of schema.org domains is exhaustive • LOD: open world assumption Heuristics for Fixing Common Errors in Deployed schema.org Microdata - Meusel and Paulheim - ESWC 2015 s:Product  s:Offer  s:price s:LocalBusiness  s:PostalAddress  s:streetAddress
  16. 16. 16 Data Property Range Violations  i.e. using a data property with an incompatible literal  Used by 9.6% of all data providers  20 most common violations: • 13 dates • 3 Urls • 2 numbers • 2 times  Comparison to LOD Compliance: • 12.06% of all Microdata documents • 4.6% of all LOD documents (Hogan et al., 2010) Heuristics for Fixing Common Errors in Deployed schema.org Microdata - Meusel and Paulheim - ESWC 2015 “a month ago” “2 pieces” “last week”
  17. 17. 17 Object Property Range Violations  i.e. using an object property with a type outside its range  Used by 8.6% of all data providers  Typical violations: • s:mainContentOfPage with s:Blog instead of s:WebPageElement  Comparison to LOD Compliance • 3.2% of all Microdata documents • 2.4% of all LOD documents (Hogan et al., 2010) Heuristics for Fixing Common Errors in Deployed schema.org Microdata - Meusel and Paulheim - ESWC 2015 Maybe a hint at a missing hierarchy relation?
  18. 18. 18 Schema.org Compliance Summary  Surprisingly high level of compliance  Providers are often not technology evangelists (unlike in LOD) • Anybody can start publishing Microdata annotated HTML  Most often higher than for LOD • Except for the confusion of data and object properties Heuristics for Fixing Common Errors in Deployed schema.org Microdata - Meusel and Paulheim - ESWC 2015 But still the number of erroneous pages could prevent data consumers to make use of the annotated data and understand the semantics.
  19. 19. 19 Identifying and Fixing Wrong Namespaces  Main errors due to missing slashes, wrong protocol and capitalization  Simple rules to handle wrong namespaces • Removal of www • Replacement of https by http • Conversion to lower case • Adding of missing slashes and removal of prefixes before schema.org  Impact: • 147 of 148 wrongly spelled namespaces could be fixed Heuristics for Fixing Common Errors in Deployed schema.org Microdata - Meusel and Paulheim - ESWC 2015
  20. 20. 20 Handling Undefined Types and Properties  Main errors due to wrong capitalization  Heuristic: Ignore capitalization when parsing entities from web pages, and replace the schema element with the properly capitalized version  Impact (together with namespace fixes): • Correct type replacement within 71% of all data providers • Correct property replacement within 65% of all data providers • Remaining data providers account for over 70% of all undefined types and properties and are hard-to-detect typos Heuristics for Fixing Common Errors in Deployed schema.org Microdata - Meusel and Paulheim - ESWC 2015
  21. 21. 21 Handling Object Properties with Literal Values  Main objects modeled as literals are s:Organization, s:Person and s:PostalAddress  Manually inspecting those values for the object properties s:author, s:creator and s:address  Impact • The heuristic could replace all misused object properties on 92,449 data providers • Might lead to changes in the type distribution • E.g. 14 million new entities of type s:PostalAddress Heuristics for Fixing Common Errors in Deployed schema.org Microdata - Meusel and Paulheim - ESWC 2015 _:1 s:author “Robert” . _:1 s:author _:2 . _:2 a s:Person . _:2 s:name “Robert” .
  22. 22. 22 Handling Property Domain Violations  Main cause are shortcuts  Heuristic to find the property R and type T for a domain violation of property s:r: One unique solution for only one of the two patterns:  Impact: • 31% of erroneous data providers could be fixed • No solution or multiple solutions for the rest Heuristics for Fixing Common Errors in Deployed schema.org Microdata - Meusel and Paulheim - ESWC 2015 _:1 “5” s:aggregatedRating s:aggregatedRating is not defined for type of _:1 _:2 s:aggregatedRating Type? Property? R s:domainIncludes s:t . R s:rangeIncludes T . s:r s:domainIncludes T . R s:rangeIncludes s:t . R s:domainIncludes T . s:r s:domainIncludes T .
  23. 23. 23 Heuristics Summary  Over 410 million wrong triples could be corrected  Over 700 million missing triples could be added  Corrections affected in total over 115.000 data providers • ~ 28% of all data providers in the data set Heuristics for Fixing Common Errors in Deployed schema.org Microdata - Meusel and Paulheim - ESWC 2015
  24. 24. 24 LD4IE Challenge @ ISWC 2015 Heuristics for Fixing Common Errors in Deployed schema.org Microdata - Meusel and Paulheim - ESWC 2015 Learn to annotate entities on HTML pages using already annotated pages as training set.  Deadline: 2015-07-15  Challenge Page: goo.gl/laF6yl  Contact: Heiko Paulheim (heiko@dwslab.de) Good Luck!
  25. 25. 25 Thank you! Questions? Feedback? Data and more insights can be found at: http://webdatacommons.org/structureddata/2013- 11/stats/fixing_common_errors.html More interesting datasets and analysis can be found at the website of WebDataCommons: http://webdatacommons.org/index.html Heuristics for Fixing Common Errors in Deployed schema.org Microdata - Meusel and Paulheim - ESWC 2015 Acknowledgement The extraction and analysis of the datasets was supported by AWS in Education Grant.

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