## 4 Results
### Q2: What Is the Type of Solution Proposed? Figure 8 (see left quadrant) presents the grouping and distribution of the different types of solutions proposed in the studies. According to the results, it can be observed that: 17 studies (60.7%) propose validations in the industry (S2, S3, S4, S5, S10, S11, S12, S13, S14, S15, S16, S17, S19, S21, S24, S25, and S28) through interviews (S15 and S21), models (S4, S5, and S28), surveys (S12, S13, S17, S24, and S25), experiments (S3, S8, S15, and S2), proposal evaluations (S10, S14), and data collection and analysis (S11 and S16); 5 studies (17.9%) propose conceptual definitions (S1, S8, S20, S26, and S27) aimed at providing a clearer overview of the subject matter; 3 studies (10.7%) describe causes, effects, impacts, and limitations (S6, S7, and S18) related to happiness and unhappiness in communities within the context of software engineering; 1 study (3.6%) proposes a method or evaluation technique (S9) to identify happiness or unhappiness through words; 1 study (3.6%) proposes a technological tool (S22) to support decision-making regarding technical debt management; and 1 study (3.6%) proposes a prediction model to identify potential \"smelly\" development communities (S23). A total of 60.7% of the studies focus on practical validations in the industry, while 17.9% propose conceptual definitions. Despite some practical solutions, there is a lack of tools and methodologies to improve welfare in agile software communities. The trend towards industrial validation highlights opportunities for future theoretical and methodological research. Although the primary articles focus on establishing a state of knowledge regarding the happiness and unhappiness of agile software communities through studies that focus on conceptual or theoretical aspects, as well as a proposed method, other types of solutions, such as processes, techniques, or practical models to address this issue in different ways, are not evidenced. Furthermore, although a tool has been developed to support decision-making, no studies were identified that propose methodological solutions or tools to diagnose software development communities and identify potential causes of unhappiness, and thus, take actions to mitigate or contain the emergence, risk, or threat, or to promote  
Figure 8: Visualization of solution types by year in a bubble chart. improvements in happiness indices in order to enhance the well-being of agile software development communities. Additionally, based on Figure 8, there is a clear trend towards industrial validation as the predominant focus in the evaluated studies, which suggests a strong orientation toward practical application in the industry in recent years. However, the number of studies in other categories remains limited, which could indicate potential areas for future research to deepen the theoretical or methodological aspects of the solutions presented. This pattern highlights the academic emphasis on developing directly applicable solutions, although there is still room for the exploration of new tools and methods. Q3: What Are the Causes That Generate Happiness and/or Unhappiness in Agile Software Development Communities? Figure 9 is based on the information presented in Tables 11 and 12, which list the causes of happiness and unhappiness identified in the primary studies, respectively. The information in the tables is organized as follows: (i) cause number; (ii) cause name; (iii) number of times the cause appears in the primary studies; (iv) identifier of the primary study (see Table 8); and (v) type of cause.