Overall statement or summary of the article and its findings in your own words

This paper is a sub-set as part of a larger research project about the consequences of happiness and unhappiness amongst software developers. It seeks to answer two specific research questions and the scope of the topic of research is clearly outlined. The research paper outlines how specific consequences affect both happiness and unhappiness of software developers while developing software and offers further lines of study to investigate the effects in greater detail.

Overall strengths and weaknesses of the article and what impact it might have in your field

The areas of strength in this article is the reliance on the SPANE instrument for the development of questions to developers and use of the Corbin and Strauss’ Grounded Theory to code responses into categories to allow for further analysis and causal inference drawing. Existing research into the impact of several states of happiness and unhappiness and their associated consequences are referenced and conclusive relationships are drawn throughout.

The areas of weakness in this article has been highlighted in the limitations section of the paper, however one area that didn't receive a mention was the fact that the working conditions of the software developers surveyed hasn't been mentioned and therefore, the impact of whether they are working in isolation, amongst a large team or in fact if they are a graduate/migrant - all of which may have an impact on the happiness/unhappiness levels. This limitation has not been mentioned in the Limitation section, nor has it been proposed as future line of study for further research.

Specific comments on strengths and weaknesses of the article and what could be done to improve it:

comments on the Abstract, Title and References

The aim of the paper is clearly outlined in the Abstract with an explanation also given as to how the current knowledge about this topic differs from what this paper sets out to achieve. The methods of study and a brief overview of the results obtained is succinct, yet informative.

The title is also informative and clearly outlines the focus of the paper. The play on the research question - "What happens when the software developers are (un) happy" is clever and serves the dual purpose of letting the readers know that the researchers aim to investigate both aspects of happiness.

The references listed seem to be broad-ranging in date as well as subject. The researchers appear to have considered specific aspects of software development tasks - such as working with pull requests, which suggests a level of granularity that will logically, help with analysing the qualitative effects of the developer being happy. There seems to be only one paper reference made to the dominant working methodology in use in software companies in the world - Agile.

comments on the Introduction and Background

The authors have presented current knowledge of the field explicitly and clearly. The knowledge gap between what is already known and what the researchers seek to find is also presented lucidly. Where the researchers have worked on previous papers and made conclusions out of that research, they have carefully outlined what was discovered and what is still yet to be discovered.

The research questions for which answers are sought are outlined clearly. There are references made to papers and current knowledge throughout the Introduction.

The Background describes in further detail the reasons for conducting the research including mentioning that the research in the field of assessing software developers' happiness/unhappiness levels is still in its infancy. The researchers also refer to their previous work in the field and outline the specific area of research they are focusing on in the background.

Comments on the Method

The process of subject selection for the study is clearly identified, albeit the sample collection timing is not specified. Although the researchers say that they have collected the email addresses of active participants in the GitHub community over 6 months, they do not specify which 6 months of the year this is. For instance, if the Christmas/New Year period was included in this 6 month sample, given that many businesses would be operating in limited capacity and the impact of the festive period may have contributed to more feelings of happiness/unhappiness.

As this paper is part of a bigger research project, the questions posed in the other papers and the variables they employ or statistical methods used in those papers are outlined for brief background purposes. It is also made clear that the present paper is employing qualitative research techniques. The two research questions used in the study are detailed in the parent research project's paper and it wasn't immediately obvious whether this was intended. It is assumed that each research paper needs to be self-sufficient and if a brief description was offered as to the statistical methods used in the parent project's papers, the questions posed in the questionnaire employed as part of this study should have been presented here.

The study methods and analysis employed have been described in section 3.3 as using the Corbin and Strauss’ Grounded Theory. The paper also describes in detail how different researchers coded the questionnaire responses and then attempted to merge them using the shared axial coding scheme. Further attempts to selectively re-code the data that did not fit the scheme is also outlined in detail and it appears that the analysis methods employed are valid and reliable. There also appears to be enough detail in the paper to replicate the study, however, as mentioned before, if some of the information that has been presented in the overarching research project was presented again in this paper, this would have been better for completeness and self-sufficiency.

Comments on the Results

The results of the study is presented clearly and in sufficient detail. The tables of data are titled and columns have a descriptive name. The categories ascribed to the feelings of unhappiness and happiness respectively in Tables 1 and 2 are described in greater detail in the text. The categories in the text are also described with specific examples of answers given by the study participants. As the research technique employed is qualitative, there are no hard statistics referenced in this paper and therefore no statistically significant results are presented. However, the categories presented to describe both happiness and unhappiness are grouped in a way that offers practically meaningful interpretations of what feelings equate to happiness or unhappiness.

Comments on Discussions and Conclusions

The researchers have done a thorough job of explaining the interpretation of the data and results as it applies to the two research questions posed. They have approached the discussion of the results from different angles - including from external and internal viewpoints as well as in terms of the categories the individual consequence falls into from both the happiness and unhappiness perspectives.

In terms of the limitations of the study, the authors do acknowledge that the GitHub sample size is more geared towards male developers and those that are not necessarily active in the field of software development. These are obvious drawbacks when it comes to sourcing the causes of happiness and unhappiness of software developers who are actively engaged in the workforce. One potential drawback that hasn't been mentioned is the fact that the working environments in which these developers do their work may also have an impact on the feelings and impacts of happiness and unhappiness.

There are strong and robust lines of study mentioned for future researchers including the authors of the paper themselves. These lines of study is likely to offer valuable insights into the happiness and unhappiness levels amongst software developers as well as those in other roles within the software engineering field.