Transcript Introduction to Mechanized Labor Marketplaces: Mechanical Turk

Introduction to Mechanized Labor
Marketplaces: Mechanical Turk
Uichin Lee
KAIST KSE
Mechanical Turk
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Begin with a project
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Break it into tasks and design your HIT
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Define the goals and key components of your project. For example, your goal might be to clean your
business listing database so that you have accurate information for consumers.
Break the project into individual tasks; e.g., if you have 1,000 listings to verify, each listing would be
an individual task.
Next, design your Human Intelligence Tasks (HITs) by writing crisp and clear instructions, identifying
the specific outputs/inputs desired and how much you will pay to have work completed.
Publish HITs to the marketplace
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You can load millions of HITs into the marketplace. Each HIT can have multiple assignments so that
different Workers can provide answers to the same set of questions and you can compare the results
to form an agreed-upon answer.
https://requester.mturk.com/tour/how_it_works
Mechanical Turk
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Workers accept assignments
– If Workers need special skills to complete your tasks, you can require that they pass a
Qualification test before they are allowed to work on your HITs.
– You can also require other Qualifications such as the location of a Worker or that they have
completed a minimum number of HITs.
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Workers submit assignments for review
– When a Worker completes your HIT, he or she submits an assignment for you to review.
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Approve or reject assignments
– When your work items have been completed, you can review the results and approve or reject
them. You pay only for approved work.
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Complete your project
– Congratulations! Your project has been completed and your Workers have been paid.
https://requester.mturk.com/tour/how_it_works
Screenshot
Screenshot
AMT Questions
• Who are the workers that complete these
tasks?
• What type of tasks can be completed in the
marketplace?
• How much does it cost?
• How fast can I get results back?
• How big is the AMT marketplace?
Analyzing the Amazon Mechanical Turk marketplace, P. G. Ipeirotis, Journal XRDS: Crossroads, 2010
Demographics of Mechanical Turk, P.G. Ipeirotis, NYU TR, 2010
Gender and Age
• Countries: 46.80% US, India: 34%, Misc: 19.2%
(from 66 different countries)
http://behind-the-enemy-lines.blogspot.com/2010/03/new-demographics-of-mechanical-turk.html
Educational Level
• Many of the workers are younger than overall
population, and this leads to higher
educational levels
Income Level
• Indian Turkers relatively have low income level
Marital Status and Household Size
• Lots of single workers
• Indian workers tend to belong to larger households
Level of Engagement on M-Turk
• Most workers spent less than a day per week, completing 20100 HITs, and earning less than $20 per week.
Motivation
• Why do you complete tasks in Mechanical Turk? Please check any of the
following that applies (multiple items possible):
– [1] Fruitful way to spend free time and get some cash (e.g., instead of
watching TV)
– [2] I find the tasks to be fun
– [3] To kill time
– [4] For "primary" income purposes (e.g., gas, bills, groceries, credit cards)
– [5] For "secondary" income purposes, pocket change (for hobbies, gadgets,
going out)
– [6] I am currently unemployed, or have only a part time job
[1]
[2]
[3]
Motivation
• Why do you complete tasks in Mechanical Turk? Please check any of the
following that applies:
– [1] Fruitful way to spend free time and get some cash (e.g., instead of watching
TV)
– [2] I find the tasks to be fun
– [3] To kill time
– [4] For "primary" income purposes (e.g., gas, bills, groceries, credit cards)
– [5] For "secondary" income purposes, pocket change (for hobbies, gadgets,
going out)
– [6] I am currently unemployed, or have only a part time job
[4]
[5]
[6]
Summary
• Significant fraction of Turkers are from US and
India (> 80% vs. 20% from misc)
• Turkers are younger (more than 50% from 21-35)
• More females (US) and more males (India)
• Turkers relatively have lower income
• Turkers relatively have smaller families
• Geographic distribution of Turkers and Internet
users is similar
Type of Tasks in M-Turk
Requester vs. Total Rewards
• Long tail nature of participation
Keywords vs. Ranks
Price Distribution
• HITgroups with a large number of HITs tend to have a low
price (e.g., $0.10)
• 90% of HITs pay less than $0.10
Posting and Serving Process
• Cumulative distribution plots:
– For each day, the value of tasks being posted by the AMT requesters,
and the value of the tasks that got completed in each day
• Median posting/completion rate: $1,040 vs. $1,155 per day
• M/M/1 queueing assumption: a task worth $1, average completion time
of 12.5 minutes
Value of posted/completed HITs in USD ($)
Posting and Serving Process
• Less posting over the weekends (requesters)
• Less work done on Monday due to less posting over the
weekends
Posting
Completion
Completion Time Distribution
Power law
distribution:
w/ alpha = -1.48
10 days
10 days
Next Week
• Taskcn (in China)
• How to use M-Turk for research?
• M-Turk test assignment