A centre of expertise in digital information management UKOLN is supported by: Approaches to automated metadata extraction : FixRep Project Emma Tonkin

A centre of expertise in digital information management Wouldn't it be nice if......computers could author our metadata for us, thus saving a lot of hassle? Mechanical metadata extraction vs manual metadata input

A centre of expertise in digital information management But... Automated tools are fallible There's never quite enough information available Templates change, different domains have different standards In short, computers are often wrong –and so are people

A centre of expertise in digital information management Hybrid approach: –Get what metadata you can –Ask the user to check and clean it if necessary Philosophy: –If the computer gets it wrong, we can fix it later The 'half a loaf' hypothesis

A centre of expertise in digital information management Wouldn’t it be nice if… …computers could fix our metadata for us? Or, more realistically, help us do this work for ourselves.

A centre of expertise in digital information management All about ‘fixing it later’, doing what we can with what we have Automated metadata extraction + metadata consistency assessment Metadata generation, evaluation, characterisation: enabling metadata triage

A centre of expertise in digital information management 1)Challenges in automated metadata extraction 2)Manual metadata generation 3)Metadata extraction in brief 4)Practical use as part of a repository deposit workflow 5)A user study comparing manual and hybrid input 6)Towards metadata triage

A centre of expertise in digital information management Whatever can go wrong... PDFs can be: –Encrypted –Corrupted –Oddly encoded –An image file without embedded text –Occurrence: ~3-6%

A centre of expertise in digital information management Character sets Ligatures, Accents, Symbols - may not always be extractable from PDFs Image © Daniel Ullrich

A centre of expertise in digital information management Document formats/layouts Many possible formats Some formats not widely supported Document layouts vary widely, esp. by discipline

A centre of expertise in digital information management 1)Challenges in metadata extraction 2)Manual metadata generation 3)Metadata extraction in brief 4)Practical use as part of a repository deposit workflow 5)A user study comparing manual and hybrid input 6)Towards metadata triage

A centre of expertise in digital information management Whatever can go wrong... (II) Function following form – interface Model adapted to suit unique user needs Data model incompletely supported Input validation issues Systematic error; typos; localisation; encoding; etc. Lots of past work in characterising manual input errors

A centre of expertise in digital information management 1)Challenges in metadata extraction 2)Manual metadata generation 3)Metadata extraction in brief 4)Practical use as part of a repository deposit workflow 5)A user study comparing manual and hybrid input

A centre of expertise in digital information management Image segmentation, templating & OCR

A centre of expertise in digital information management Working from text There are a number of possible states (ie. title, author, , affiliation, abstract) Directed graph with probabilities – Markov chain: for example, Title Author Affil.

A centre of expertise in digital information management Hidden Markov Model We cannot directly see these states – only the words But we can gather statistics on the correlation between the words and the underlying states, to inform guesses as to how the data should be segmented This may be expressed in terms of an HMM Bayesian statistics used across term appearance

A centre of expertise in digital information management Example parse Confirmation-Guided Discovery of First-Order Rules, PETER A. FLACH, NICOLAS LACHICHE... Confirmation-Guided Discovery of First-Order Rules, PETER A. FLACH, NICOLAS LACHICHE Self-correcting, to the extent that the knowledge base grows as new papers are added to the collection

A centre of expertise in digital information management 1)Challenges in metadata extraction 2)Manual metadata generation 3)Metadata extraction in brief 4)Practical use as part of a repository deposit workflow 5)A user study comparing manual and hybrid input 6)Towards metadata triage

A centre of expertise in digital information management Aims Adaption of existing interfaces Enhancing rather than rewriting Cross-platform, accessible interface Simple reusable REST API, metadata as DC/XML

A centre of expertise in digital information management Sample interfaces

A centre of expertise in digital information management Sample interfaces

A centre of expertise in digital information management Architecture

A centre of expertise in digital information management Using what we know...

A centre of expertise in digital information management 1)Challenges in metadata extraction 2)Manual metadata generation 3)Metadata extraction in brief 4)Practical use as part of a repository deposit workflow 5)A user study comparing manual and hybrid input 6)Towards metadata triage

A centre of expertise in digital information management Question: “Do people accept ‘hybrid’ interfaces?” Here’s one we did earlier…

A centre of expertise in digital information management Hypotheses Correcting extracted metadata is faster than entering or cutting-and-pasting metadata. The resulting metadata has fewer errors when the user is provided with already extracted metadata to correct. User satisfaction with a system is higher if it 'tries' to extract metadata, even if it fails. Measured: speed and accuracy of entering information manually versus hybrid entry, and qualitatively, the user-satisfaction

A centre of expertise in digital information management Results: Timing Hybrid faster under both conditions (Summary of median times)‏

A centre of expertise in digital information management Results: Accuracy Tested against ground-truth Keyword accuracy: First keyword listed was relevant for 46% of the publications. The top two were relevant in 66%; the top-5 cover 81% of all desired keywords. Manual metadata accuracy: –Few users use cut and paste –Capitalisation, punctuation frequently differs –Synonyms are accidentally substituted Hybrid closer to ground-truth, and more complete, but results not clear-cut.

A centre of expertise in digital information management Qualitative results Most users preferred the hybrid mode Most perceived it to be faster than manual data entry Few believed the hybrid approach to be more accurate; in practice, there was no significant difference in quality between hybrid and manual approach Both were good - quality

A centre of expertise in digital information management Discussion Results support hypotheses People prefer the hybrid interface, and found it more satisfying to use Accessibility issues exist, but can be overcome The punchline: one subject actually preferred manual entry because the hybrid system filled in metadata fields that he preferred to leave empty – ie. it did more than the subject wanted!

A centre of expertise in digital information management 1)Challenges in metadata extraction 2)Manual metadata generation 3)Metadata extraction in brief 4)Practical use as part of a repository deposit workflow 5)A user study comparing manual and hybrid input 6)Towards metadata triage

A centre of expertise in digital information management MetRe prototype (2008) Characteristic classes of individual/systematic error highlighted Nb. local and general best practice. Uses: ranking, browsing, correcting systematic error Uses info from intra-/inter-repository harvested metadata to identify patterns, rank occurrences and co-occurrences

A centre of expertise in digital information management v

A centre of expertise in digital information management

A centre of expertise in digital information management Issues Discipline/domain-specific issues Lots of information required to do this right (see metadata schema/terminology registry) Some APs present particular difficulties, such as SWAP (FRBR structure, linking objects by ‘Scholarly Work’)

A centre of expertise in digital information management Approach Generally dependent on heuristics over available data Powered by very specific functions (classifiers, validation, etc…) Potentially expensive, not always domain-independent

A centre of expertise in digital information management Future work More! –Data –Filters (input/output formats) –Methods –Evaluation –Service availability (mail me for announcements!)

A centre of expertise in digital information management Conclusion Metadata creation can be supported through software Specific problem sets in metadata triage Work continues in the FixRep project

A centre of expertise in digital information management Conclusion (II) Formal Metadata Extraction/evaluation Metadata review process Accessibility metadata Entity extraction (named entities, geographical, temporal [k-int!]) Repository integration

A centre of expertise in digital information management Thanks! Comments/Questions?