RecSys 2016 Talk: Feature Selection For Human Recommenders
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Transcript of RecSys 2016 Talk: Feature Selection For Human Recommenders
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Human Computation At Stitch Fix
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Heavy and repetitive computation
Large-scale working memory
Large-scale long-term memory
Context sensitivity/nuance
Aesthetic judgements
Relationship building
Novel inferences
Unstructured data
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Processes information to make recommendations
Can specify internal mechanisms
Can specify the data being used
Recommendations improve with better features (data)
Needs to be trained and tuned
Comes with internal mechanisms
Can consider the entire world
Proprietary and confidential
Processes information to make recommendations
Can specify internal mechanisms
Can specify the data being used
Recommendations improve with better features (data)
Needs to be trained and tuned
Comes with internal mechanisms
Can consider the entire world
Proprietary and confidential
Determine what they’re processing
Determine what they should be
processing
Change/shape what they’re processing
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Determine what they’re processing
Determine what they should be
processing
Change/shape what they’re processing
Make more recommendations
Deliver those recommendationsReceive feedback
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1: Determining what they’re processing
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If someone isn’t attending to something, but you’re showing it anyways you might
■ Make your worker less efficient (slower)■ Fatigue them (unnecessary filtering)■ Lose opportunities for including something more useful
Figure out what your human workers are attending to while they make their recommendations
If they aren’t attending to a feature, then they’re not making recommendations off of it
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Exploration
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‘Online’ Observations
What you get
○ Ability to reduce the hypothesis space
○ Higher granularity observations ○ Time-dependent observations
(when is something considered)
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Mouse Tracking
Cheap measure of attention
Non-invasive
Easy widespread deployment
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Eye Tracking
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[Visual] search patterns lie somewhere between random and systematic…. humans will attempt a more systematic search, but will still suffer from imperfect memory.
(Nickles et al., 2003)
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Eye Tracking
Resistant to strategy
Deterministic
Higher accuracy
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AREA OF INTEREST (AOI)
Eye Tracking
Resistant to strategy
Deterministic
Higher accuracy
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Features You Want To Select!
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2: Determining what they should be
processing
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You’re interested in overall performance and can optimize for whatever is most important to you
■ True hits, false positives, false negatives■ Processing time
Given the features that they’re using, which ones produce the best recommendations?
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The Logic:○ Workers may vary in what features they use○ Look for correlations between attention to features and positive
metrics
Allows you to learn the optimal features amongst your current candidates
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Feature Drop Out Studies
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Feature Drop Out Studies A/B
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Feature Drop Out Studies
Logic
Show a feature to one cell, and remove it for another
If a positive difference in performance is observed, then that feature promotes better outcomes
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Feature Drop Out Studies
Optimal Conditions
A highly controlled “offline” environment
○ Allows for true participant randomization
○ Allows for repeated measures○ Allows for high “internal validity”
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Task-relevantbackground information(optional)
Ability to provide a response - track accuracy, RT, confidence, etc.
Trial-specific stimuli - use historic data with known outcomes
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Correct ~ Condition + (1|participant_id)
Condition differences
Feature promotes better recommendations
Feature either isn’t considered or makes no difference to recommendations if it is
No condition differences
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Further Use Of ‘Online’
Observations
What you get
○ Ability to determine whether there are certain times at which certain features are beneficial
○ Ability to figure out how information is searched for
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-Status: loved-Department: top-Color: purple
-Status: loved-Department: dress-Color: green
-Status: hated-Department: pants-Color: orange
-Status: ...-Department: ...-Color: ...
Start with a study to determine correlations
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Multiple metrics possible
■ Overall trajectories (http://www.eyetracking-r.com/)■ Saccade patterns■ Fixation times and locations
Correlate with success
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correct ~ fixated_on_loves + fixated_on_color_matches + … + (1|participant_id) …
Factors predict success
Attention to features may promote better recommendations
Attention to features may make no difference to recommendations
Factors don’t predict success
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correct ~ condition + … + (1|participant_id)
Follow up with a full experiment to determine whether the behavior
actually causes better recommendations
Manipulation congruent with ‘positive’ behaviors
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3: Shaping What They’re
Processing
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Controlled Lab Study Full A/B Test
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Stitch Fix’s “Styling Lab”
Full A/B Test in the live styling
environment
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Behavior Shaping : Humans :: Tuning : Computers Algorithms
Can be “in the moment”
● UX Changes● Directed Attention
Can be more sustained
● Training
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Change how the information is displayed - exploit human perception (consult UX)
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Testing
● Create questions relevant to what you want to train
● Have participants complete them
● Use IRT to determine question difficulty
Training
● Order questions by difficulty
● Have those being trained complete them in that order
● Given feedback on performance along the way
● Reinforce key concepts
Experimental Approach!
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This approach is grounded in Cognitive research!
Progressive Alignment prescribes giving people tasks that they’re more likely to succeed at, then progressively making those tasks harder
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Processes information to make recommendations
Can specify internal mechanisms
Can specify the data being used
Recommendations improve with better features (data)
Needs to be trained and tuned
Comes with internal mechanisms
Can consider the entire world
Proprietary and confidential
Questions?