Some Thoughts on Tagging

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Some Thoughts on Tagging
Marti Hearst UC Berkeley
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Outline

• What are Tags?
• Organizing Tags for Navigation
• Facets and faceted navigation
• How to (semi)automatically create facet
  hierarchies
• Whats up with Tag Clouds?

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Social Tagging

• Metadata assignment without all the bother
• Spontaneous, easy, and tends towards single terms
• Usually used in the context of social media

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Example from del.icio.us
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The Tagging Opportunity

• At last! Content-oriented metadata in the large!
• Attempts at metadata standardization always end
  up with something like the Dublin Core
• author, date, publisher, yaaawwwwnnn.
• Ive always thought the action was in the subject
  metadata, and have focused on how to navigate
  collections given such data.

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The Tagging Opportunity

• Tags are inherently faceted !
• It is assumed that multiple labels will be
  assigned to each item
• Rather than placing them into a folder
• Rather than placing them into a hierarchy
• Concepts are assigned from many different content
  categories
• Helps alleviate the metadata wars
• Allows for both splitters and lumpers
• Is this a bird or a robin
• Doesnt matter, you can do both!
• Allows for differing organizational views
• Does NASCAR go under sports or entertainment?
• Doesnt matter, you can do both!

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Tagging Problems

• Tags arent organized
• Thorough coverage isnt controlled for
• The haphazard assignments lead to problems with
• Synonymy
• Homonymy
• See how this author attempts to compensate

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Tagging Problems / Opportunities

• Some tags are fleeting in meaning or too personal
• toread todo
• Tags are not professional
• (I personally dont think this matters)
• Great example from Trant
• "Anecdotal evidence also shows that
  professional cataloguers find the basic
  description of visual elements surprisingly
  difficult a curator exhibited significant
  discomfort during this description task. When
  asked what was wrong, he blurted out "everything
  I know isn't in the picture".
• Investigating social tagging and folksonomy in
  the art museum with steve.museum", J. Trant, B.
  Wyman, WWW 2006 Collaborative Tagging Workshop

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Investigating social tagging and folksonomy in
the art museumwith steve.museum", J. Trant, B.
Wyman, WWW 2006 Collaborative Tagging Workshop
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What about Browsing?

• I think tags need some organization
• Currently most tags are used as a direct index
  into items
• Click on tag, see items assigned to it, end of
  story
• Co-occurring tags are not shown
• Grouping into small hierarchies is not usually
  done
• del.icio.us now has bundles, but navigation isnt
  good
• IBMs dogear and RawSugar come the closest
• I think the solution is to organize tags into
  faceted hierarchies and do browsing in the
  standard way

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Faceted Navigation and Flamenco
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The Problem With Hierarchy

• Most things can be classified in more than one
  way.
• Most organizational systems do not handle this
  well.
• Example Animal Classification

Skin Covering
otter penguin robin salmon wolf cobra bat
Locomotion
Diet
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The Problem with Hierarchy

• Inflexible
• Force the user to start with a particular
  category
• What if I dont know the animals diet, but the
  interface makes me start with that category?
• Wasteful
• Have to repeat combinations of categories
• Makes for extra clicking and extra coding
• Difficult to modify
• To add a new category type, must duplicate it
  everywhere or change things everywhere

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The Problem With Hierarchy
start
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The Idea of Facets

• Facets are a way of labeling data
• A kind of Metadata (data about data)
• Can be thought of as properties of items
• Facets vs. Categories
• Items are placed INTO a category system
• Multiple facet labels are ASSIGNED TO items

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The Idea of Facets

• Create INDEPENDENT categories (facets)
• Each facet has labels (sometimes arranged in a
  hierarchy)
• Assign labels from the facets to every item
• Example recipe collection

Ingredient
Cooking Method
Chicken
Stir-fry
Bell Pepper
Curry
Course
Cuisine
Main Course
Thai
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The Idea of Facets

• Break out all the important concepts into their
  own facets
• Sometimes the facets are hierarchical
• Assign labels to items from any level of the
  hierarchy

Preparation Method Fry Saute Boil
Bake Broil Freeze
Desserts Cakes Cookies Dairy
Ice Cream Sorbet Flan
Fruits Cherries Berries Blueberries
Strawberries Bananas Pineapple
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Using Facets

• Now there are multiple ways to get to each item

Preparation Method Fry Saute Boil
Bake Broil Freeze
Desserts Cakes Cookies Dairy
Ice Cream Sherbet Flan
Fruits Cherries Berries Blueberries
Strawberries Bananas Pineapple
Fruit gt Pineapple Dessert gt Cake Preparation gt
Bake
Dessert gt Dairy gt Sherbet Fruit gt Berries gt
Strawberries Preparation gt Freeze
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The Flamenco Interface

• Fine Arts Museum Example

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Advantages of the Approach

• Systematically integrates search results
• reflect the structure of the info architecture
• retain the context of previous interactions
• Gives users control and flexibility
• Over order of metadata use
• Over when to navigate vs. when to search
• Allows integration with advanced methods
• Collaborative filtering, predicting users
  preferences

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Advantages of Facets

• Cant end up with empty results sets
• (except with keyword search)
• Helps avoid feelings of being lost.
• Easier to explore the collection.
• Helps users infer what kinds of things are in the
  collection.
• Evokes a feeling of browsing the shelves
• Is preferred over standard search for collection
  browsing in usability studies.
• (Interface must be designed properly)

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Related WorkAutomated Tag Organization

• Some efforts are on tag prediction
• Mishne 06
• Uses IR techniques to find the closest tagged
  documents, uses their tags to assign new tags.
  Measures on how well new tags predicted
• Xu et al. 06
• Use tags that have already been predicted for a
  document to predict which to show to a new user
  who is tagging the document
• Some efforts on tag organization
• Brooks Montanez 06
• Tries to see if tags can predict document
  clusters, which in my book arent really
  categories
• After clustering based on text they try to induce
  a tag hierarchy by agglomerative clustering the
  text. Results not described in detail
• Begelman et al. 06
• Use clustering and tag co-occurrence to find
  associated tags. Not clear what the
  organizational goal is

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RawSugar

• A company/website that organizes tags from blogs
  into facets
• They are undergoing a revamp, will move to
  channels
• However, nothing published on this
• (presumably, patents filed)

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How to Create Facet Hierarchies?

• Our Approach Castanet
• (Stoica Hearst, to appear at HLT-NAACL 07)

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Example Recipes (3500 docs)
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Castanet Output (shown in Flamenco)
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Castanet Output (shown in Flamenco)
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Castanet Output (shown in Flamenco)
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Example Biology Journal TitlesCastanet Output
(shown in Flamenco)
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Castanet Algorithm

• Leverage the structure of WordNet

Documents
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1. Select Terms
Build tree
Comp. tree
Documents
Select terms
Get hypernym paths

• Select well distributed
• terms from collection

WordNet
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2. Get Hypernym Path
red
blue
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3. Build Tree
Build tree
Comp. tree
Documents
Select terms
Get hypernym paths
WordNet
red
blue
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4. Compress Tree
Build tree
Comp. tree
Documents
Select terms
Get hypernym paths
WordNet
color
chromatic color
red, redness
blue, blueness
green, greenness
red
blue
green
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4. Compress Tree (cont.)
Build tree
Comp. tree
Documents
Select terms
Get hypernym paths
WordNet
color
color
chromatic color
red
blue
green
red
blue
green
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5. Divide into Facets
Divide into facets
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Disambiguation

• Ambiguity in
• Word senses
• Paths up the hypernym tree

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How to Select the Right Senses and Paths?

• First build core tree
• (1) Create paths for words with only one sense
• (2) Use Domains
• Wordnet has 212 Domains
• medicine, mathematics, biology, chemistry,
  linguistics, soccer, etc.
• Automatically scan the collection to see which
  domains apply
• The user selects which of the suggested domains
  to use or may add own
• Paths for terms that match the selected domains
  are added to the core tree
• Then add remaining terms to the core tree.

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Castanet Evaluation Method

• Information architects assessed the category
  systems
• For each of 2 systems output
• Examined and commented on top-level
• Examined and commented on two sub-levels
• Also compared to a baseline system
• Then comment on overall properties
• Meaningful?
• Systematic?
• Likely to use in your work?

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CastaNet Evaluation Results

• Results on recipes collection for
  Would you use this system in your work?
• Yes in some cases or yes, definitely
• Castanet 29/34
• LDA 0/18
• Subsumption 6/16
• Baseline 25/34
• Average response to questions about quality
  (4 strongly agree)

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Will Castanet Work on Tags?

• Class project by Simon King and Jeff Towle, 2004
• 1650 captions captured from mobile phones
• Blocks with Grandpa, Weezer , A veterans day
  tour of berkeley in front of south hall., Bad
  photo, Kitchen, Jgj
• Wanted to organize them.
• Use the CastaNet wordnet-based facet-hierarchy
  creation algorithm
• by Stoica Hearst, to appear at HLT-NAACL 07
• Had to first remove proper names

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Example Photos Captions (King Towle)
very scary x-mas tree
Hp presentation
chasing a cat in the dark
My cat
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• instrumentality, (112)
• vehicle (26)
• car (9)
• bike (8)
• vessel, watercraft (4)
• mayflower (2)
• ferry (1)
• gig (1)
• truck (3)
• airplane (2)
• device (20)
• machine (7)
• computer (4)
• laptop (1)
• sander (1)

• container (16)
• vessel (7)
• bottle (5)
• water_bottle (2)
• jug (1)
• pill_bottle (1)
• bath (2)
• bowl (1)
• can (2)
• backpack (1)
• bumper (1)
• empty (1)
• salt_shaker (1)
• furniture, piece of furniture, article of
  furniture (12)
• seat (8)
• bench (2)
• chair (2)
• couch (2)
• lounge (1)

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Research Questions for Tags Search

• The role of interface on tag convergence
• There seems to be a big effect
• Would be really interesting to experiment with
  this
• Also, for facet grouping
• Anchor text vs. tags?
• How are they the same how do they differ?
• How to get tag expertise?
• Right now, in many cases it is least-common-denomi
  nator
• ESP-game

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Whats up with Tag Clouds?
What does a typical tag cloud look like?
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Definition

• Tag Cloud A visual representation of social
  tags, organized into paragraph-style layout,
  usually in alphabetical order, where the relative
  size and weight of the font for each tag
  corresponds to the relative frequency of its use.

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Definition

• Tag Cloud A visual representation of social
  tags, organized into paragraph-style layout,
  usually in alphabetical order, where the relative
  size and weight of the font for each tag
  corresponds to the relative frequency of its use.

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flickrs tag cloud
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del.icio.us
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del.icio.us
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blogs
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• ma.gnolia.com

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NYTimes.com tags from most frequent search terms
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IBMs manyeyes project
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Amazon.com Tag clouds on term frequenies
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Alternative Semantic Layout

• Improving Tag-Clouds as Visual Information
  Retrieval Interfaces, Yusef Hassan-Monteroa, 1
  and Víctor Herrero-Solana, InSciT2006
• Tags grouped by similarity, based on clustering
  techniques and co-occurrence analysis

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I was puzzled by the questions

• What are designers and authors intentions in
  creating or using tag clouds?
• How do they expect their readers to use them?

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On the positive side

• Compact
• Draws the eye towards the most frequent
  (important?) tags
• You get three dimensions simultaneously!
• alphabetical order
• size indicating importance
• the tags themselves

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Weirdnesses

• Initial encounters unencouraging
• Some reports from industry
• Is the computer broken?
• Is this a ransom note?

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Weirdnesses

• Violates principles of perceptual design
• Longer words grab more attention than shorter
• Length of tag is conflated with its size
• White space implies meaning when there is none
  intended
• Ascenders and descenders can also effect focus
• Eye moves around erratically, no flow or guides
  for visual focus
• Proximity does not hold meaning
• The paragraph-style layout makes it quite
  arbitrary which terms are above, below, and
  otherwise near which other terms
• Position within paragraph has saliency effects
• Visual comparisons difficult (see Tufte)

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Weirdnesses

• Meaningful associations are lost
• Where are the different country names in this tag
  clouds?

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Weirdnesses

• Which operating systems are mentioned?

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Tag Cloud Study (1)

• First part compared tag cloud layouts
• Independent Variables
• Tag size
• Tag proximity to a large font
• Tag quadrant position
• Task recall after a distractor task
• 13 participants effects for size and quadrant
• Second part compared tag clouds to lists
• 11 participants
• Tested recognition (from a set of like words) and
  impression formation
• Alphabetical lists were best for the latter no
  differences for the former

• Getting our head in the clouds Toward
  evaluation studies of tagclouds, Walkyria
  Rivadeneira Daniel M. Gruen Michael J. Muller
  David R. Millen, CHI 2007 note

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Tag Cloud Study (2)

• 62 participants did a selection task
• (find this country out of a list of 10 countries)
• Independent Variables
• Horizontal list
• Horizontal list, alphabetical
• Vertical list
• Vertical list, alphabetical
• Spatial tag cloud
• Spatial tag cloud, alphabetical
• Order for non-alphabetical not described
• Alphabetical fastest in all cases, lists faster
  than spatial
• May have used poor clouds (some people couldnt
  see larger font answers)

• An Assessment of Tag Presentation Techniques
  Martin Halvey, Mark Keane, poster at WWW 2007.

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A Justifying Claim

• You get three dimensions simultaneously!
• alphabetical order
• size indicating importance
• the tags themselves
• but is this really a conscious design decision?

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Solution Celebrity Interviews

• I was really confused about tag clouds, so I
  decided to ask the people behind the puffs
• 15 interviews, conducted at foocamp06
• Several web 2.0 leaders
• 5 more interviews at Google and Berkeley

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A Surprise

• 7 interviewees DID NOT REALIZE that alphabetical
  ordering is standard.
• 2 of these people were in charge of such sites
  but had had others write the code
• What was the answer given to what order are tags
  shown in?
• hadnt thought about it
• dont think about tag clouds that way
• random order
• ordered by semantic similarity
• Suggests that perhaps people are too distracted
  by the layout to use the alphabetical ordering

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Suggested main purposes

• To signal the presence of tags on the site
• A good way to get the gist of the site
• An inviting and fun way to get people interacting
  with the site
• To show what kinds of information are on the site
• Some of these said they are good for navigation
• Easy to implement

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Tag Clouds as Self-Descriptions

• Several noted that a tag cloud showing ones own
  tags can be evocative
• A good summary of what one is thinking and
  reading about
• Useful for self-reflection
• Useful for showing others ones thoughts
• One example comparing someone elses tags to
  owns one to see what you have in common, and
  what special interests differentiate you
• Useful for tracking changes in friends lives
• Oh, a new girls name has gotten larger he must
  have a new girlfriend!

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Tag Clouds as showing Trends

• Several people used this term, that tag clouds
  show trends in someones behavior
• Trends are usually patterns across time, which
  are not inherently visible in tag clouds
• To note a trend using a tag cloud, one must
  remember what was there at an earlier time, and
  what changed
• tracking the girls names example
• This suggests a reason for the importance of the
  large tags draws ones attention to what is big
  now versus was used to be large.
• Suggests also why it doesnt matter that you
  cant see small tags.

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New Perspective Tag Clouds are Social!

• Its not about the information!
• Not surprising in retrospect tagging is in large
  part about the social aspect
• Seems to work mainly when the tags can be seen by
  many
• Even better when items can be tagged by many and
  seen by many
• What does this mean though when tag clouds are
  applied to non-social information?

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Follow-up Study

• Informed by the interview results, we search for,
  read, and coded web pages that mentioned tag
  clouds.
• Looked at about 140 discussions
• Developed 21 codes
• Looked at another 90 discussions
• Used web queries tag clouds, usability tag
  clouds, etc
• Sampled every 10th url
• 58 personal blogs
• 20 commercial blogs
• 10 commercial web pages
• rest from group blogs and discussion lists
• Doesnt tell us what people who dont write about
  tag clouds think.

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The Role of Popularity

• Popularity in the sense that tag clouds (and
  tagging) are trendy and popular.
• Some people liked the visualization, but their
  popularity made them less appealing
• Famous post Tag clouds are the new mullets
• Led to self-consciousness about liking them
• Many complained about unaesthetic cloud designs
• Little consensus on if they are a fad or have
  staying power
• Popularity also in the sense of the large font
  size for more popular tags
• Many people like the prominence of large tags,
  but several commented on the tyranny of the
  popular

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The Role of Navigation

• Opinions vary
• Many simply state they are useful for navigation,
  but with no support for this claim
• Some claim the compactness makes navigation
  easier than a vertical list
• Some object to the varying font size on
  scannability
• Others object to the lack of organization
• Overall, there is no evidence either way that we
  could find in the blog community

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Aesthetic Considerations

• Disagreement on the aesthetic and emotional
  appeal, especially for lay users.
• Those who like them find them fun and appealing
• Those who dont find them messy, strange, like a
  ransom note
• Informal reports with first time users who are
  not in the Web 2.0 community are negative

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Trends again

• As in the interviews, the benefit of trends was
  mentioned many times.
• There is another sense of trend as tendency or
  inclination, and this might be what people mean.

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Summary of Stated Reasons for Tag Clouds(Note
some refuted by studies)
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Tag Clouds as Social Information

• An emphasis that tag clouds are meant to show
  human behavior.
• We found reports of people commenting on other
  uses that were invalid because they did not
  reflect live user input
• One blogger noted the incongruity of an online
  library using keyword frequencies in a tag cloud
  rather than having it reflect patrons usage of
  the collection.
• An online community noticed one sites cloud
  didnt change over time and realized the sizes
  were decided by marketing. This was greated with
  derision.

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Implications

• Assume tag clouds are meant to reflect human
  mental activity (individual or group)
• Then what might seem design flaws from an
  information conveyance perspective may not be
• A large part of the appeal is the fun and
  liveliness.
• The informality of the layout reflects the human
  activity beneath it.

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Judith Donath, CACM 45(4), 2002

• Traditional data visualization focuses on
  making abstract numbers and relationships into
  concrete, spatialized images the goal is to
  highlight important patterns while also
  representing the data accurately. This is a fine
  approach for social scientists studying the
  dynamics of online interactions. Yet for our
  purpose it is also important that the
  visualization evoke an appropriate intuitive
  response representing the feel of the
  conversation as well as depicting its dynamics

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Judith Donath, CACM 45(4), 2002

• One argument for deliberately designing
  evocative visualizations for online social
  environments is the existing default textual
  interfaces are themselves evocative, they simply
  evoke an aura of business-like monotony rather
  than the lively social scene that actually
  exists.''

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Tag Cloud Alternatives

• Provided by Martin Wattenberg

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Conclusions

• Social tagging is, in my view, a terrific way to
  get good content metadata.
• I think automated techniques can do a lot to help
  clean them up and organize them.
• They are an inherently social phenomenon, part of
  social media, which is a really exciting area.
• The socialness of social media can yield
  surprises, like tag clouds.