The Invisible Hands of Time: How Timezones Shape Online Communities

The InvisibleHands of Time:

How Timezones ShapeOn-line Communities

Wybo Wiersma

Oxford Internet Institute

[email protected]

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


Wybo Wiersma

Introduction

Hypotheses

Threads

Networks

Statistics

Conclusion

Questions

References

Hypotheses


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


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


Wybo Wiersma

Introduction

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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


Wybo Wiersma

Introduction

Hypotheses

Threads

Networks

Statistics

Conclusion

Questions

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


Wybo Wiersma

Introduction

Hypotheses

Threads

Networks

Statistics

Conclusion

Questions

References

Threads


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


Wybo Wiersma

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Threads: A specimen


Wybo Wiersma

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Threads: User locations


Wybo Wiersma

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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


Wybo Wiersma

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Threads: Created per hour


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


Wybo Wiersma

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Threads: Posts hours after prompt created


Wybo Wiersma

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Threads: Replies clock


Wybo Wiersma

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Networks


Wybo Wiersma

Introduction

Hypotheses

Threads

Networks

Statistics

Conclusion

Questions

References

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


Wybo Wiersma

Introduction

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Conclusion

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References

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


Wybo Wiersma

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Networks: Whole


Wybo Wiersma

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Networks: Core (both > 3)


Wybo Wiersma

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Networks: Core directed (any > 6)


Wybo Wiersma

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Networks: Clocks core (> 5) vs periphery (< 6)


Wybo Wiersma

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Threads: Prolific users aligned by timezone


Wybo Wiersma

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Statistics: Numbers don’t lie


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


Wybo Wiersma

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References

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


Wybo Wiersma

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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)


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


Wybo Wiersma

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Conclusion: Time’s up


Wybo Wiersma

Introduction

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Threads

Networks

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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


Wybo Wiersma

Introduction

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Threads

Networks

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Conclusion

Questions

References

Questions

Any questions ?


Wybo Wiersma

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References

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Wybo Wiersma

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