Automatic vs manual indexing Focus on subject indexing Not a relevant question? –Wherever full text is available, automatic methods predominate Simple inverted index of text words More sophisticated vector-based models with weighting/ranking facilities Assignment systems which map to controlled terms

Automatic vs manual indexing Manual indexing –Gather doc’s across languages, vocabularies etc –Adapt to retrieval needs of particular user groups –Offer vocabulary assistance to users in search process –Adapt to needs for varying degree of specificity –Allow consistent retrieval over time –Allow for navigation, hierarchically or to related topics

Automatic vs manual indexing User problems –Express need (problem) in terminology appropriate to Problem System terminology Changing user habits –Searching vs. browsing

Automatic vs manual indexing Problems with manual indexing –Cost –capacity –Consistency & quality –Mapping between systems –Constructing & maintaining vocabularies

Automatic vs manual indexing Integration automatic / manual –Automatic categorization –Term mapping (”topics”) –Ranking mechanisms