\chapter{Discussion}

The ITS analysis of the investigated communities shows mixed results. Some communities show an increase in sentiment while others are not affected at all or show a decrease in sentiment. The StackOverflow community has a fairly stable average sentiment before the change. The average sentiment jumps to a higher level and keeps rising after the change is introduced. Furthermore, the number of 1st questions from new contributors starts rising drastically after the change while prior levels stagnate. Also, the follow-up questions start increasing slightly. The votes score trend takes a new direction 9 months before the change and is unrelated to it. The change has a positive effect on the StackOverflow community. 

Beside StackOverflow, 5 other communities seem to profit from the change: AskUbuntu, ServerFault, stats.stackexchange.com, tex.stackexchange.com, and unix.stackexchange.com. AskUbuntu shows an interesting zig-zag pattern in the average sentiment graph. Also, the average sentiment falls before the change and raises thereafter, indicating that the change works for this community. However, further data is needed to see if the zig-zag pattern repeats itself. The number of 1st questions starts increasing again after the change stopping the downward trend before that. 

On stats.stackexchange.com the average sentiment falls before the change but since the change, the downward trend stops and the sentiment starts to rise slowly, suggesting the change has a positive effect on the community. This is supported by the increase in the number of 1st and followup questions by new contributors. The vote score takes a dip after the change but starts to recover after 12 months which could be the result of another factor. 
%TODO see text in results, vote score and 1st questin same timeframe

In the tex.stackexchange.com community sentiments are stable before the change and show a stark rising pattern after the change. The change seems to work for this community but future data will be necessary to see if the rising pattern continues in the shown manner. The votes score ITS does not fit the model and values before and after the change indicate a linear downward trend. However, the number of 1st questions increases slightly after the change while the prior trend shows a decreasing development. 

unix.stackexchange.com also shows a decreasing pattern prior and a rising pattern after the change. The vote score analysis shows a fairly linear downward trend before and after the change and is not affected by it. However, the number of 1st questions by new contributors starts to drastically increase while before the change the levels are constant, indicating this community also profits from the change. 

On ServerFault the sentiment rises gradually before the change, jumps upward by a small value when the change is introduced and the sentiment falls slowly thereafter but the levels are pretty stable over the analyzed period. The vote scores show the change has a huge impact on the community. The previously decreasing trend jumps up by a large amount. However, the vote score rapidly returns to levels right before the change. Contrary, the number of first questions turns direction and starts increasing at the same rate it is falling previously.

%~ - -
The other communities do not seem to profit from the change so clearly. The average sentiment stays constant on MathOverflow before the change and decreases afterward. However, the sentiment levels start increasing six months before the change and are unrelated, indicating the sentiment values are not particularly affected by the change. The vote score is steadily increasing before the change and the crashes down shortly after the change. However, the vote score is very high compared to other communities. The number of 1st questions stabilizes after the change compared to the slight downward previously. 

math.stackexchange.com shows a downward trend before and after the change for sentiment and vote score. The sentiment ITS is particularly affected by the low sentiment values at the end and future data is required to determine if this trend continues. However, the number of 1st questions stabilizes a bit after changes and follow up questions even see and a slight increase after the change. 

The electronics.stackexchange.com community has a similar pattern for the sentiment value and vote scores compared to math.stackexchange.com. However, the sentiment values seem to recover after about 12 months and future data is required to see if the rise at the end of the period is a long term trend. The rising number of first questions of new contributors stops at the change date and transition into a decreasing pattern. 

SuperUser shows an odd pattern. The average sentiment values and votes scores are stable before the change and decrease dramatically shortly afterward. However, the sentiment recovers after 12 months. The ITS model chosen in this thesis is not able to capture the apparent pattern. However, the number of 1st question skyrockets indicating a huge influx of new users. The time frames of the falling sentiment values and vote scores, and the rising number of first questions overlap, indicating the huge influx of new users is responsible for the falling patterns.

% similarities in results and differences
% so: only community that shows a clear improvement when comapred to prior to change sentiment
% mse not really changing, downward trend before and after, probably to the low last 5 values, its does not say much
% mo: sentiments largely the same before and after, regression falling due to how its works, its does not say much
% au: show intresting zigzag pattern: falling then gradually rising
% sf: sentiments fairly stable change not really detectable
% su: sneitments crashed down after change but recovered later, its model cannot catch this
% ele: steadily falling, same upward trend in the end, maybe senitments recover i future data
% stats: falling before change and drop at change but afterward seniemnts stabilized even rising 
% tex: sentiments took up a bit after the change; change seems to works
% unix: sentiments falling prior but gainig after; change seems to work

By and large, the change introduced by the StackExchange team has a clear positive effect on more than half of the investigated communities. Two of the communities, SuperUser and stats.stackexchange.com, have a delayed temporary decrease in sentiment which recovers after about 12 months, which may be attributable to the larger influx of new contributors. The selected ITS model is not designed to capture the sentiment pattern of these communities. math.stackexchange.com is not really affected by the change, although the number of 1st questions stabilized a bit and follow-up questions from new contributors increase again. MathOverflow shows a similar picture.

% expectations from before the experiment and how they match with results
% did change from SE produce the desired results?

Some investigated data sets show interesting patterns. StackOverflow shows the clearest results of all the investigated communities and closely resembles the example ITS shown in section 3. The result matches the expectation, that advising answerers to remember the code of conduct when answering questions from new contributors will increase the welcomingness and friendliness of the community, and shows that the change introduced by the StackExchange team works well for this community. The AskUbuntu community shows an interesting zig-zag pattern where sentiment gradually rises over time and then falls abruptly.

% interesting single results?

The average sentiment of the StackOverflow community is the most stable in terms of deviation from the regression. This is expected as StackOverflow is the largest community by far and has the most questions created by newcomers. On the other hand, MathOverflow is the sparsest community and has the least amount of questions from new contributors. The level of the average sentiment also varies greatly between communities. stats.stackexchange.com has the highest level of average sentiment compared to the other communities, whereas, tex.stackexchange.com has the lowest level average sentiment. MathOverflow has the highest level of vote scores by far. Also, in most communities, the number of questions from new contributors slowly decreases over time. This may be a result of the filling of gaps in the knowledge repository over time.

% as expected #answers per month vary greatly -> mabye into data sets section
% some communties have a high average sentiment compared to others
% mathoverflow very sparse, stackoverflow densest obviously as biggets community 100x more users
% fewer questions by new users over time? + explaination

%future research
% investigate different change pattern and why they occured

