## 1 Introduction
Some natural language processing (NLP) techniques such as cleaning [17], parts-of-speech (POS) tagging [18], WordNet lemmatization [19], and N-grams [20] are applied to get potential candidate terms that can be interpreted as user requirements in later stages. The requirements are then analyzed to get variable requirements (VR) and common requirements (CR) from the initial set of requirements. Generally, we can collect user demands for a specific theme from various social networks. However, measuring values in software engineering is complex but also essential for the systematic study of values in software engineering [21]. Therefore, we also focused on other information of SNS users which we called personal attributes, for instance, (emoticon), country, gender, and language, to draw more vigorous conclusions. The requirements which are elicited by considering personal attributes are called value-oriented requirements in our study. The definition of value-oriented requirements is derived from the study of [PERSON] et al. [22]. The authors mentioned that'socio-political' issues such as values, people's feelings and emotions are often considered as problems in the RE process. The authors presented a value-based RE method that first introduced a taxonomy to deal with socio-political issues in RE to complement prevailing analysis of non-functional requirements. The authors introduced new considerations into the RE process by paying attention to individual users' values, motivationsand emotions. We selected 'gender' and 'country' attributes due to the fact that different regions (countries) can have gender-specific values or values in general that can be useful to better understand users' demands. However, the study of [PERSON] et al. [22] addressed value-based RE, meaning that the engineering process considers values to perform development activities. Our value-oriented RE approach identifies users' needs as one of the requirements, not process activities. Mostly, this research article contributes in three-fold. First, we present an SNS-based RE process to conduct RE activities for SPL. Our approach focusses on VR and CR which is not addressed in related work. Second, we propose a methodology to determine VR and CR considering the influencing factors of tweets or comments. Third, the validity of this proposed approach is measured by conjoining with Facebook and Twitter, which allows users to express their opinion without any temporal and spatial constraints. Furthermore, a controlled experiment consisting of two teams each consisting of 15 members was performed to test the proposed approach and its applicability compared to traditional RE process. The smartwatch domain was selected as a subject in our controlled experiment to exercise our proposed approach. We envision the relevance of this study within new software paradigms like cloud computing, mobile applications, and software ecosystems. In software ecosystems, anonymous end-users are not within instant reach of software development organizations and support provided by conventional RE approaches is insufficient. Therefore, smart wearables developers, cloud service developers, game developers or \"Internet of XYZ\" ecosystems could use our RE approach to elicit user requirements. This paper is organized as follows: Section 2 discuss the SNS-based RE process for SPL while in Section 3 controlled experiment design and results are described. In Section 4, we analyze the outcomes from both RE approaches. In Section 5 we discuss threats to the validity of this study while Section 6 describes related work and finally, Section 7 concludes this article with some future research directions.