\chapter{Introduction}

%grammarly checks

%TODO more text here
%sachen von related work wiederholen
%DONE es gibt so viele commu .. neue kommen, machen comm sterben, 
%DONE was machen die site admins
%DONE was hat stackexchange gemacht ein beispeil

%DONE different types of communities: social exchange(facebook, twitter, div messaging apps), social support platforms, information exchange (community knownledge platforms (CQA, forums, wikis, ...), ...)

With the introduction of the Web 2.0 and its core feature of user interaction, users interact with each other in online communities. These communities come in various shapes and forms. There are communities for social interaction, for instance, Facebook\footnote{\url{https://facebook.com}}, Twitter\footnote{\url{https://twitter.com}}, and instant messaging apps. There are communities for social support, i.e. communities where users have certain common qualities, for instance, illnesses. There are also communities with the purpose of information exchange. Information exchange platforms can be grouped into expert and community knowledge platforms. While expert platforms are rarely known and often only used by niche groups, community knowledge platforms are widely known and used by the general public. Community knowledge platforms can be divided into 1) wikis, for instance, Wikipedia\footnote{\url{https://wikipedia.org}}, 2) forums, and 3) Q\&A platforms, for instance, \emph{Yahoo! Answers}\footnote{\url{https://answers.yahoo.com}}, \emph Quora\footnote{\url{https://quora.com}}, and StackExchange\footnote{\url{https://stackexchange.com}}.

StackExchange is a Q\&A platform and consists of 174 communities\footnote{\url{https://stackexchange.com/tour}}. Each community evolves around a specific topic, for instance, StackOverflow focuses on software engineering, and AskUbuntu focuses on the Ubuntu operating system. This distinguishes StackExchange from other Q\&A sites such as \emph{Yahoo! Answers} where no such differentiation into topics exists. %TODO ref

% stackexchange and how it developed via stackoverflow \cite{mamykina2011design} good description of SO
% Design Lessons from the Fastest Q&A Site in the West \cite{mamykina2011design} early investigation of so
% goto place for programming questions (SO)
% social media
% knowledge archive 
% different to top-down forums %TODO success of SO paper
% write new numbers about so %TODO



%-->

%DONE challenges of running a community: initial setup, onboarding, keeping angagements, regulation
%DONE -> add mentor ship program+desc rough description: exampl for onboarding
%DONE stackexhange tries many things over the years: mentorship program+ref,  list more examples here, see section 2

Communities face different challenges during their lifetime\cite{kraut2012building}. In the beginning, bootstrapping the community and gaining a critical mass of users is the main challenge. In the following phase, community growth is the main challenge. In the third phase, the goal is to keep the community in a lively and ordered state. The main challenges in this phase are onboarding new users, ensuring steady user engagement and contributions, and regulation. Running a community also includes challenges in other areas, for instance, technical, financial, and personnel challenges. A community has to solve all these challenges to a certain degree to exist and continue existing. Many communities have been created over the years and a lot of these communities also went extinct. A recent example of a community shutdown of a larger-scale community is \emph{Yahoo! Answers} which shut down in May 2021\footnote{\url{https://help.yahoo.com/kb/SLN35642.html}}.

StackExchange is continually working on improving their platform. Their team implemented several changes to the platform to tackle different challenges that arose over time, for instance, updating the \emph{code of conduct} to ensure a more friendly tone in user interactions\footnote{\url{https://meta.stackexchange.com/questions/240839/the-new-new-be-nice-policy-code-of-conduct-updated-with-your-feedback}}, improving the review queue for reported content for moderators\cite{ponzanelli2014improving}, or the \emph{Mentorship Research Project}\cite{ford2018we}\footnote{\url{https://meta.stackoverflow.com/questions/357198/mentorship-research-project-results-wrap-up}}.

The \emph{Mentorship Research Project} was a research project to improve the onboarding process of new users. In the study new users who created their first question had the option the let their question be reviewed by a mentor (a user familiar with the community). The mentor would review the question and suggest changes to the question, for instance, more context to the question. The user would then adjust their question and post it in the community. The result of the study was that mentored questions were received significantly better than non-mentored questions. Although this is just a research project, StackExchange could create some automated systems to help new users during their onboarding phase.

In August 2018, the StackExchange team introduced a small change that may have had a huge impact on the platform. They added a new feature to visibly highlight questions from new contributors, as part of their effort to make the site more welcoming for new users\footnote{\url{https://meta.stackexchange.com/questions/314287/come-take-a-look-at-our-new-contributor-indicator}}. Specifically, members who want to answer a question created by a new contributor are shown a notification in the answer box that this question is from a new contributor. The StackExchange team hopes that this little change encourages members to be more friendly and forgiving toward new users.
% write about the change investigated
% stackexchange new contriutor post: https://meta.stackexchange.com/questions/314287/come-take-a-look-at-our-new-contributor-indicator?cb=1
% what did change intend?

This thesis evaluates whether this change has a real impact on the community and if so how the community reacts. For this analysis, this thesis uses a 2-step approach:
\begin{enumerate}
 \item Gather data:
  \begin{enumerate}
   \item sentiment values of the answers submitted to questions of new contributors
   \item vote score on questions of new contributors
   \item number of questions new contributors ask
  \end{enumerate}
 \item Perform an \emph{Interrupted Time Series} (ITS) analysis on the gathered data
\end{enumerate}
This thesis utilizes Vader \cite{hutto2014vader}, a sentiment analysis tool, to measure the sentiments of the answers submitted to questions of new contributors. The ITS analysis evaluates whether the change achieved its purpose of making the platform more welcoming.
Higher sentiment values, higher vote scores, and higher question counts indicate more friendly community interactions and welcomingness towards new contributors. Also, when new contributors have a good experience with their first question, they are more likely to post further questions.
% how is change investigated by this thesis
% vader library

This thesis investigates the ten largest communities of the StackExchange platform measured by the number of posts. This includes most prominent communities, for instance, StackOverflow, MathOverflow, MathStackExchange, AskUbuntu, and SuperUser as well as some lesser-known communities.
% write about other communities (e.g. i investigated)



%write a bit about results

%write about next chapters
The remaining part of this thesis is structured as follows: Section 2 explains StackExchange and its communities, how it works, and shows related work. Section 3 shows the method this thesis uses for analysis in detail. 
Section 4 contains the investigated datasets. Results are presented in Section 5 and discussed in Section 6. Section 7 concludes this thesis.





%other chapters
% how the new contributor thing works https://meta.stackexchange.com/questions/314472/what-are-the-exact-criteria-for-the-new-contributor-indicator-to-be-shown
