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A popular view of online communities is that they transcend time and place. As threads and comments are posted, however, the ensuing online-discussions unfold over time. Not only does timing determine which threads participants will see first when they arrive, but also which comments have not already been extensively replied to. By affecting who interacts with whom during the circadian cycle, time-pressure at the level of threads could in turn shape the social ties that form. Coupled with time-zone differences, this would make online communities a lot less global than generally believed. A case-study of the Hacker News community was conducted to measure time-effects. Hacker News caters to people interested in web-startups. It has approximately 100,000 unique daily visitors from all over the world, and receives about 2,500 posts per day. Fourty days of data was collected, and geo-locations were acquired for three thousand users. In a preliminary analysis, strong time-pressure effects were found at the thread-level. For social ties between users, moderate, but statistically significant effects were found as well; especially for users at the edge of the network. Even the two-week gap between the introduction of daylight savings time in the US and UK, was found to have an impact on peoples network distance during that time. These findings might limit the validity of purely social interpretations of on-line reply structures, as well as the extent to which (large) on-line communities can be considered real communities, rather than imagined communities that are primarily shaped by the flow of conversation.
Citation preview
The InvisibleHands of Time:
How Timezones ShapeOn-line Communities
Wybo Wiersma
Oxford Internet Institute
23 May 2013
The InvisibleHands of Time:How TimezonesShape On-lineCommunities
Wybo Wiersma
Introduction
Hypotheses
Threads
Networks
Statistics
Conclusion
Questions
References
Introduction
In this talk I:
• Will catch time red-handed
• At impacting the structure an on-line community
? namely; Hacker News
• Time sets the stage for interaction
Your speaker:
• 1st year DPhil student
? at the Oxford Internet Institute
• Sr. Software engineer in Sillicon Valley last year
The InvisibleHands of Time:How TimezonesShape On-lineCommunities
Wybo Wiersma
Introduction
Hypotheses
Threads
Networks
Statistics
Conclusion
Questions
References
Hypotheses
The InvisibleHands of Time:How TimezonesShape On-lineCommunities
Wybo Wiersma
Introduction
Hypotheses
Threads
Networks
Statistics
Conclusion
Questions
References
Hypotheses: Why care
Social interpretations of reply-structures
• Are common in SNA
? reciprocity, bonding, friendship
Underlying assumptions:
• On-line communities
? work similarly to off-line ones
• On-line Global Village
? is actually global
Yet if time foremostly determines replies
• Social explanations might be spurious
The InvisibleHands of Time:How TimezonesShape On-lineCommunities
Wybo Wiersma
Introduction
Hypotheses
Threads
Networks
Statistics
Conclusion
Questions
References
Hypotheses: Previous work
Papers on reply-structures
• None circadian, none on 24-hour scale
More remotely relevant
• How threads unfold on Slashdot (Kaltenbrunner)
• Usenet discussions unfold over multiple days
• Cycles in MUDs/Internet/mobile traffic
The InvisibleHands of Time:How TimezonesShape On-lineCommunities
Wybo Wiersma
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Hypotheses
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Hypotheses: Theory
Social mechanisms (Elster, Hedstrom)
• Look at individual interactions
? micro to macro emergence
Structuration theory (Giddens)
• Environment affords/shapes choices
? besides, and through agency
Imagined communities (Anderson)
• On-line communities like nation states
? not based on personal social ties
The InvisibleHands of Time:How TimezonesShape On-lineCommunities
Wybo Wiersma
Introduction
Hypotheses
Threads
Networks
Statistics
Conclusion
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References
Hypotheses: Why care
Hypothesis 1)
• There is a time-pressure effect at level of threads
? users mainly reply to new threads/posts? threads are mostly saturated within a few hours
Hypothesis 2)
• What appears social in reply-structures
? is dictated by the thread time-pressure effect? and peoples different circadian rythms
The InvisibleHands of Time:How TimezonesShape On-lineCommunities
Wybo Wiersma
Introduction
Hypotheses
Threads
Networks
Statistics
Conclusion
Questions
References
Threads
The InvisibleHands of Time:How TimezonesShape On-lineCommunities
Wybo Wiersma
Introduction
Hypotheses
Threads
Networks
Statistics
Conclusion
Questions
References
Threads: Hacker News
Hacker News is like Slashdot
• Can comment on stories
? but posted by members
• Rating / time determines ranking
? (r − 1)/(t + 2)1.8
? separates time effects from ordering
• 100k daily visitors (large)
• Ran by Paul Graham (Y-combinator incubator)
? for startup community? very international
The InvisibleHands of Time:How TimezonesShape On-lineCommunities
Wybo Wiersma
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Threads: A specimen
The InvisibleHands of Time:How TimezonesShape On-lineCommunities
Wybo Wiersma
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Threads: User locations
The InvisibleHands of Time:How TimezonesShape On-lineCommunities
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Threads: Data
Data collected
• Over 40 days (in 2011)
? 3.5k threads? 100k posts? by 13.3k users
So 90 threads, 2.5k posts per day
The InvisibleHands of Time:How TimezonesShape On-lineCommunities
Wybo Wiersma
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Threads: Created per hour
The InvisibleHands of Time:How TimezonesShape On-lineCommunities
Wybo Wiersma
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Threads: Time pressure effects
Time pressure effect
• Threads created in time
? discussions unfold over time
• People arrive at different times
? new threads seen first? duplicate replies not appreciated? early replies read more
• Thus new threads (most productively) replied to
Time determines which threads people reply to
• Thus whose posts they interact with
The InvisibleHands of Time:How TimezonesShape On-lineCommunities
Wybo Wiersma
Introduction
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Threads: Posts hours after prompt created
The InvisibleHands of Time:How TimezonesShape On-lineCommunities
Wybo Wiersma
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Threads: Replies clock
The InvisibleHands of Time:How TimezonesShape On-lineCommunities
Wybo Wiersma
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Networks
The InvisibleHands of Time:How TimezonesShape On-lineCommunities
Wybo Wiersma
Introduction
Hypotheses
Threads
Networks
Statistics
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Networks: The social fabric
Time-pressure effects
• Confirmed at thread level
? most replies are to new threads
Social interpretation of reply-networks
• Largely spurious if time determines
? who people maintain ties with
On-line communities
• Would be largely imagined communities
The InvisibleHands of Time:How TimezonesShape On-lineCommunities
Wybo Wiersma
Introduction
Hypotheses
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Conclusion
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Networks: Types
Reply-networks
• Whole
? unidirectional replies sufficient
• Core
? reciprocated replies (cutoff > 3)
Colouring
• 3-hour sliding windows
? in which user posts most
• 8:00 - 11:00,
? 9:00 - 12:00, etc
• Same colouring as replies clock
The InvisibleHands of Time:How TimezonesShape On-lineCommunities
Wybo Wiersma
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Networks: Whole
The InvisibleHands of Time:How TimezonesShape On-lineCommunities
Wybo Wiersma
Introduction
Hypotheses
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Networks: Core (both > 3)
The InvisibleHands of Time:How TimezonesShape On-lineCommunities
Wybo Wiersma
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Networks: Core directed (any > 6)
The InvisibleHands of Time:How TimezonesShape On-lineCommunities
Wybo Wiersma
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Networks: Clocks core (> 5) vs periphery (< 6)
The InvisibleHands of Time:How TimezonesShape On-lineCommunities
Wybo Wiersma
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Threads: Prolific users aligned by timezone
The InvisibleHands of Time:How TimezonesShape On-lineCommunities
Wybo Wiersma
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Statistics: Numbers don’t lie
The InvisibleHands of Time:How TimezonesShape On-lineCommunities
Wybo Wiersma
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Statistics: Permutation test
Tested fraction of ties that showed:
• Reciprocity
• Transitivity (triadic closure)
24 one-hour windows over 40 days:
• Base-case
? networks for same window every day
• 10k permutations
? different random window every day
The InvisibleHands of Time:How TimezonesShape On-lineCommunities
Wybo Wiersma
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Statistics: Permutation test
Reciprocity in 24 same 0.113 - 0.148
• For random windows
? average 0.087 (never larger, p 0.000)
Transitivity in 24 same 0.016 - 0.025
• For random windows
? average 0.014 (41/10k larger, p 0.004)
Very significant time-effects
The InvisibleHands of Time:How TimezonesShape On-lineCommunities
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Statistics: Least squares distance
Median circadian time-difference
• Between posts
? per network-distance
10 minutes per hop (1 to 4 hops)
• in core (> 3 reciprocated)
30 minutes per hop (4 hops)
• in periphery (< 6 posts)
The InvisibleHands of Time:How TimezonesShape On-lineCommunities
Wybo Wiersma
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Statistics: Daylight savings time
Daylight savings time is introduced
• In a phased manner between the UK and US
• US (13th of March) two weeks earlier than UK (27th)
US West Coast and UK users compared
• Distance smaller after US DST introduced
? and larger again after UK DST
• 8 Hour-difference reduced to 7 for two weeks
? 3.65 to 3.53 (0.12 hop distance)
Small, but highly significant difference
The InvisibleHands of Time:How TimezonesShape On-lineCommunities
Wybo Wiersma
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Conclusion: Time’s up
The InvisibleHands of Time:How TimezonesShape On-lineCommunities
Wybo Wiersma
Introduction
Hypotheses
Threads
Networks
Statistics
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Questions
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Conclusion
Time-pressure effects
• Confirmed at thread level
? most replies are to new threads
Time effects on network
• Very significant (but small) effects
• Stronger at periphery than at core
? core users on-line 20/7, bridge
Hands of time set the stage
Limits:
• Measures/statistics
• Different for different communities
The InvisibleHands of Time:How TimezonesShape On-lineCommunities
Wybo Wiersma
Introduction
Hypotheses
Threads
Networks
Statistics
Conclusion
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References
Questions
Any questions ?
The InvisibleHands of Time:How TimezonesShape On-lineCommunities
Wybo Wiersma
Introduction
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References
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