\chapter{Methodology}

% sentiment calculation via vaderlib, write whole paragraph and explain, also add ref to paper \cite{hutto2014vader}
% data sets as xml files from archive.org \cite{archivestackexchange}

%cleaning data
% broken entries, missing user id
% answers in html -> strip html and remove code sections, no contribution to sentiment


% calc sentiment for answers

% about the change 
% https://meta.stackexchange.com/questions/314287/come-take-a-look-at-our-new-contributor-indicator \cite{post2018come}
% https://meta.stackexchange.com/questions/314472/what-are-the-exact-criteria-for-the-new-contributor-indicator-to-be-shown \cite{sonic2018what} ; change date = 2018-08-21T21:04:49.177
% new user indicator visible for 1 week ...



% differences in avg sentiment
% look at plots and write something that fits



%interrupted time series
% ref tutorial paper \cite{bernal2017interrupted}
% often used in medical fields to see if changes have an effect
% used same tensors as describe in paper, show formula and how it works, 3 tensors describe tensors and what they capture
% explain why i chose this model, captures the change, more complex model would capture more but also get more complicated, these 3 tensors are enough to see the impact
% fitting every value not aggregated values, aggregated values would have different weights, weights are too far spread, contrary to paper where person years are more or less constant
% single value fitting is better, no weight issues, as weights are taken care of via more values
% if one month has more values than another then that month affects its more as more values are present
%