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Dynamics of libre software communities

Introduction to empirical studies aboutcontributions to Wikipedia.

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1. Contextual framework

● Libre and open source software have been thoroughly studied.

● However, that is not the case for open contents creation.– Wikipedia is the most successful example of

libre contents creation projects.● A freely accessible and editable encyclopaedia.

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2. Wikipedia features

● Based on MediaWiki.

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2. Wikipedia features

● Embedded tools in MediaWiki.

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2. Wikipedia features

● Wiki style to add and update contents.– It supports multimedia contents, image

galleries, bibliography references, mathematical equations...

● Provide many templates for automatic arranging and indexing of contents.– Table of contents.– Archive pages.– Transcluded pages.

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2. Wikipedia features● Talk pages.

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2. Wikipedia features

● Everyone can edit contents.– Respect NPoV.– Provide sources. Do not use propietary

content.● http://en.wikipedia.org/wiki/Wikipedia:Annotated_article

– Trustworthy contents?● Nature magazine's study about accuracy of

Wikipiedia articles.

– Vandalism.– “Edit wars”.

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3. Main areas of study.

● We can study many aspects in Wikipedia.– General statistics and evolution in time.– Community related parameters and content

creation process.● Author's reputation.

– Article contents: mainly quality.– Content semantic...– Social networks...

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4. “Measuring Wikipedia”● By Jakob Voss.

– Focused on the German edition.– Exponential growth.– Articles' size ditribution --> tends to log-norm– Distinct authors/article

● Power law γ=2,7

– Distinct articles/author● Power law γ=1,5

– Edits/author● Power law γ=0,5

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4. “On the evolution of Wikipedia”

● By Almeida, Mozafari and Cho.– Revision and creation of articles.

● Follows a self-similar process.

– Number of articles contributed per user.● Decreasing over time.

– Time between edits to an article.● Power law distribution.

– Users tend to focus their contributions on a small set of articles.

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4. “Studying cooperation and conflicts...”

● By Viégas, Wattemberg and Dave.– Types of vandalism.

● Mass deletion, offensive copy, phony copy...● Half of mass deletions reverted within 3 mins.

– Visualization of negotiation process.● Edit wars --> zig-zag patterns.

– Contents of pages with at least 100 edits tend to grow linearly.

– Superb visualization tool-->History flow.

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4. “On the inequality of contributions...”

● Ortega, Gonzalez-Barahona and Robles.– Gini coefficients (tot. num. revisions).

● Between 0.925 and 0.963.● It tends to decrease as the number of authors and

the number of articles grow.

– Evolution in time of Gini coefficients.● Stabilized between 80-85% in the top-ten

language editions (last 2 years).

– Japanese language edition.● Outlier values --> deserves further investigation.