Hello everybody,
I usually lurk the list so I hope you won't mind the bit of self-promotion here but ... you might be interested in this poster paper I presented at ICWSM 2010:
http://www.aaai.org/ocs/index.php/ICWSM/ICWSM10/paper/view/1517

We were looking at the distribution of user activity periods in Wikipedia and we had the same problem of defining when a user stops contributing for good. We also used a hard threshold, which means that the resulting sample is truncated, and you have to take this into account when fitting the data to a distribution. We found that a mixture of two log-normals describes the data very well. This means that the are two characteristic time scales that describe user participation: short- and long-time users. Short-time users for example stay on average 30 minutes before stopping contributing.

Another paper (by Yang et al.) at ICWSM this year performed a survival analysis similar to what Felipe's talking about, but on data from Q&A communities:
http://www.aaai.org/ocs/index.php/ICWSM/ICWSM10/paper/view/1466

Best,

G

Il 10.08.10 23.49, Luca de Alfaro ha scritto:
It's difficult to tell when a person leaves, because ... you never know if a contribution they made is the last one. 
A measure would be "how many users have done an edit in the last month", and this is actually an incredibly simple DB query to run (how fast it runs, is another question).  This can tell you how the number of users is evolving.  Hey, I could run this on my wikitrust database, if the Foundation does not wish to do this :-) 
Another measure, which is slightly harder but not much to compute, is the average time a user who does an edit has been registered. 
Together these two figures (across time) could give you a pretty good picture of what is going on. 

Luca


On Tue, Aug 10, 2010 at 2:38 PM, Felipe Ortega <glimmer_phoenix@yahoo.es> wrote:
Hello guys.

First of all, kudos for this initiative! It's great that all researchers in this list can get to know the names and interests of WMF staff working on same topics.

Additional context for Piotr. Believe me, it's really challenging to define a set of clear, and *exact* conditions to consider that any wikipedian ceased to contribute.

For our analysis published by WSJ last November, we followed similar requirements to those in the Former Contributors Survey. In particular, we established 3 months of inactivity as a "reasonable" period to consider that an editor took a long break. The main difference is that in the Survey they focus on editors who reached at least a reasonable number of lifetime revisions (20-99), while we included everyone.

I already broke down the net gain curve for different cohorts, according to number of edits, and there is no significant change in the trends (I believe that the meaningful info is the slope, not the numbers).

For what is worth, I think the best constructive critic we received about this approach came from Jimmy Wales. Jimmy explained a useful twist to the methodology, that they seem to be applying for internal metrics at Wikia.

Instead of trying to measure how many people "left", which will always have methodological drawbacks, we can ask the following question: what percentage of editors survived up to a certain age?

For instance: what's the percentage of editors who made at least 20 lifetime edits who are still active one month later? Three months later? And then: is that percentage improving, constant, or getting worse over time?

Indeed, limiting the scope to recorded revisions (the only event we can certainly measure) we avoid many of these methodological problems.

I'm still spending time with flagged-revisions, but in case Howie or anybody else is interested, it shouldn't be difficult to have a look at this.

BTW, Howie thanks for uploading the survey slides. Terrific the work you did, guys.

Cheers,
Felipe.

--- El mar, 10/8/10, Piotr Konieczny <piokon@post.pl> escribió:

> De: Piotr Konieczny <piokon@post.pl>
> Asunto: Re: [Wiki-research-l] WMF Staff Introductions.
> Para: "Research into Wikimedia content and communities" <wiki-research-l@lists.wikimedia.org>
> Fecha: martes, 10 de agosto, 2010 20:21
> Welcome!
>
> I have to say that
> http://strategy.wikimedia.org/wiki/Former_Contributors_Survey_Results
> of
> which I've just learned from your post is an excellent
> piece of
> research, one that was needed for a very long time.
>
> One question comes to mind: we now, roughly, how many
> editors we are
> gaining per months. Are there any estimates on how many we
> are losing
> (per month, year, total)? I cannot find such numbers in
> that survey.
>
> --
> Piotr Konieczny
>
> Parul Vora wrote:
> > Hello everyone,
> >
> > We (most of the current staff at the Wikimedia
> Foundation currently
> > engaging in research) had a chance to meet some of you
> at Wikisym and
> > Wikimania this year and thought it would be nice to
> introduce ourselves
> > and say hi to all of you! All of us have joined WMF in
> the past two
> > years and are working on projects or research
> questions that may be
> > relevant or of interest to all of you. Also, as far as
> I know, we are
> > all new to this list and will hopefully be talking and
> collaborating
> > with you more in the future - both here and on the
> Meta Research page.
> >
> > So, in no particular order, some introductions from
> all of us:
> >
> >  From Nimish <http://wikimediafoundation.org/wiki/User:Nimish_Gautam>
> > (ngautam@wikimedia.org):
> Hi, I'm Nimish Gautam. I started with the
> > foundation in 2009 doing development for the Usability
> Initiative, which
> > focused on new editors. I like analyzing user behavior
> to figure out how
> > people use the tools we give them (turning templates
> into a programming
> > language, who would've guessed?) and spotting trends
> so we can improve
> > those tools to help people accomplish what it is
> they're trying to do.
> > Currently I'm doing qualitative and quantitative
> research on user
> > behavior for the foundation and its various projects,
> and very
> > interested in finding ways of chunking all this
> information together to
> > make pretty, compelling, informative resources so
> people know what's
> > going on in the wikiverse and hopefully want to be a
> part of it.
> >
> >  From Howie
> > <http://wikimediafoundation.org/wiki/Staff#User_Experience_Programs>
> > (hfung@wikimedia.org):
> Hello! I'm Howie and I'm a Senior Product Manager
> > at the Wikimedia Foundation. As a product person, I'd
> like to work with
> > the community towards more data-driven decision
> making. One area I'm
> > particularly interested in is getting a better
> understanding of our
> > user's lifecycle with our projects -- how they come to
> the projects, how
> > they start contributing, their experiences as a
> contributor, why they
> > leave, and why they return. I like to use both
> quantitative and
> > qualitative methods to obtain as complete a picture as
> we need to guide
> > our decisions. On the quantitative side, I'm working
> on getting better
> > web analytics for our projects. I'm also interested in
> any data mining
> > projects along these lines (e.g., contribution
> behavior, user lifecycle
> > patterns, etc.). On the qualitative side, I worked on
> the "Why Editors
> > Leave Wikipedia" survey and would be interested in
> other qualitative
> > measurements (e.g., interviews, surveys, focus
> groups). If you're
> > interested in any of the above topics, please drop me
> a line.
> >
> >  From Amy
> > <http://wikimediafoundation.org/wiki/Staff#Public_Policy_Initiative>
> > (aroth@wikimedia.org):
> Hi, I'm Amy, the Research Analyst for the Public
> > Policy Initiative
> > <http://outreach.wikimedia.org/wiki/Public_Policy_Initiative>.
> My task
> > is to assess the project's impact on: U.S. public
> policy article
> > quality, public policy categorization, new articles,
> and new
> > contributors. Through the project I have focused on
> article quality
> > assessment, and worked with the community to add a
> quantitative value to
> > the current article assessment
> > <http://en.wikipedia.org/wiki/Wikipedia:WikiProject_United_States_Public_Policy/Quality_rating#Rubric>.
> > As a data analyst, I am interested in improving data
> accessibility from
> > Wikipedia. In my dreams, I envision data from the
> assessment tools that
> > exist within Wikipedia are captured in a real-time
> database, so that we
> > can observe what is currently happening in Wikipedia
> and how it is
> > evolving in the present, rather than having to use
> data dumps to get
> > snapshots of the state of Wikipedia. I have experience
> analyzing and
> > designing surveys and would like to use that
> experience to take a more
> > in depth look at contributor demographics and
> motivations. I am excited
> > to be a part of this huge collaborative project with a
> mission to make
> > knowledge accessible.
> >
> >  >From me, Parul Vora
> > <http://wikimediafoundation.org/wiki/User:Parulvora>
> > (pvora@wikimedia.org):
> Hi Everyone! I'm a researcher and designer with a
> > focus on participatory and collaborative spaces. I
> started at the
> > Wikimedia Foundation in 2009 and moving forward have
> interest in:
> > creating new forms of participation (beyond editing)
> on the projects
> > that better engage a wider audience with the content
> and each other;
> > assessing, evaluating and addressing the demographic
> and cultural biases
> > in our projects; and exploring location, culture and
> language as they
> > affect the development patterns of different language
> Wikipedias in an
> > effort to identify potential for experimentation and
> catalysis in
> > younger projects. I'm currently exploring the
> potential effect feedback
> > systems (article ratings, expert reviews,
> visualizations of an article's
> > history or a user's contributions) can have on the
> engagement of
> > readers, actions of editors, and the quality of
> content over time. I
> > like infovis, ux research, and unresearched innovation
> and I am
> > interested in learning more about research with
> wikipedia on motivation,
> > behavioral economic modeling and/or game theory, using
> geolocative data,
> > mobile experiences, and profiling and trend
> visualizations......and your
> > work too!
> >
> > Let us know if you're interested in learning more,
> participating in, or
> > contributing to our efforts. And drop any of us a line
> if we could learn
> > from or contribute to what you've been working
> on.......
> >
>
>
> _______________________________________________
> Wiki-research-l mailing list
> Wiki-research-l@lists.wikimedia.org
> https://lists.wikimedia.org/mailman/listinfo/wiki-research-l
>





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