## 5 Discussion  
Using text mining and probabilistic topic modeling techniques, this study analyzed the semantic content of job postings for big data jobs. This analysis uncovered seven expertise roles, 32 skills, and six competency areas required for big data professions. A high percentage (70%) of big data professionals have \"developer\" or \"engineer\" as their primary role, which is a significant inference. This finding was also emphasized in previous studies. [PERSON] et al. (2018) identified four roles as \"Business Analysts\", \"Data Scientists\", \"Developers\", and \"System Managers\" in their study [4]. Our findings overlap with three of these four roles. We determined the results for \"engineer\", \"architect\", \"manager\", and \"consultant\" in different ways. We found that the \"architect\" position is approximately three times more in demand than the \"administator\" position. However, [PERSON] et al. (2018) added \"Architect\" to \"System Managers\" [4]. These results are significant indicators of the diversification and evolution of big data roles and skills over time. According to their study, the \"Architect\" role is part of the engineering family [4]. However, according to our findings, the percentage of the \"architect\" role is extremely high. It is also seen that they should have different skills from \"engineers\" and \"developers\". On the other hand, the \"consultant\" role among the specialist roles, unlike other studies, is another remarkable finding. Due to the rapidly changing and transforming work dynamics, it is seen that the role of \"consultant\" is becoming increasingly important for big data professions. [PERSON] et al. (2018) described program managers and data consultants as roles within the family of business analysts [4]. In the literature, \"consultant\" has not been highlighted as the primary role [4, 10, 14]. One of our further findings is that \"project management\" proficiency is the most sought-after \begin{table}
\begin{tabular}{c|c|c|c|c|c|c|c} \hline \hline
**Topics (Skills)** & **Description** & **Description** & **Description** & **Description** & **Description** & **Description** \\ \hline Communication Skills & 5 & 3 & 6 & 9 & 3 & 7 & 3 & 7 \\ \hline Big Data Tools & 1 & 2 & 4 & & 9 & 6 & 9 & 6 \\ \hline Analytical Skills & & & 10 & 1 & 5 & 4 & 6 & 5 \\ \hline Big Data Architecture & 6 & 1 & & 8 & 5 & 5 & 5 \\ \hline Big Data Processing & 6 & 1 & 2 & 8 & 6 & & 5 \\ \hline Remote Development & 3 & 5 & 7 & & 10 & 4 \\ \hline Business Analytics & & & 5 & 2 & 4 & & 7 & 4 \\ \hline Business Applications & 10 & & & 7 & 8 & 3 \\ \hline Google Cloud & & 10 & 3 & & & 10 & 3 \\ \hline Amazon EMR & 8 & & 8 & & & 2 & 3 \\ \hline Information Security & 4 & & & & 8 & 4 & 3 \\ \hline Project Management & & & 9 & 1 & & 1 & 3 \\ \hline Scalable Systems & 9 & 9 & & & & 2 \\ \hline Agile Development & 7 & 8 & & & & 2 \\ \hline Data Visualization & & & 3 & 10 & & 2 \\ \hline Troubleshooting & & & 7 & 3 & 2 \\ \hline Data Analytics & 4 & & 6 & & 2 \\ \hline Programming Languages & 2 & 7 & & & 2 \\ \hline Decision-making & & 5 & 2 & & 2 \\ \hline Bachelor Degree & & 10 & & 1 \\ \hline Distributed Systems & & & 9 & 1 \\ \hline Machine Learning & & 4 & & 1 \\ \hline Hadoop Ecosystem & & & 2 & 1 \\ \hline Data Warehousing & & & 1 & 1 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Ranking of the top 10 skills for each of the expertise roles. skill for \"manager\" and \"consultant\" positions. In this sense, experts who assume the role of \"consultant\" are expected to have senior management skills. Our second discovery is that big data skills contain six core proficiency areas that include \"big data knowledge\" (36.30%), \"developer skills\" (20.25%), \"big data analytics\" (14.88%), \"cloud services\" (10.51%), \"soft skills\" (10.16%), and \"technical background\" (7.90%). This finding revealed that the required skills for big data jobs include a wide range of competency areas.