# Systematic Literature Review on Test Case Selection and Prioritization: A Tertiary Study
## 2 Research Methodology
### Research Questions  
The research questions were described and categorized into five parts. The categories then were further divided to provide the associated research questions. These questions form the basis of the current survey analysis of the studies. The details of the development of research questions are as follows:  
RQ 1. To get basic information of available secondary texts in TCS&P. **RQ 1.1:**_What is the distribution of secondary texts on TCS&P over the different online databases?_  
This RQ will enhance the knowledge of online databases in which secondary studies can be quickly found. **RQ 1.2:**_What is the evolution of the number of secondary studies published in TCS&P over the years?_  
The expansion/compaction of the research field on TCS&P can be acknowledged by increasing/decreasing secondary studies in the area. New secondary studies are performed only when the existing ones have become obsolete or show missing aspects in their analysis. In both cases, researchers work in secondary research areas for which high demand is maintained in the research community. The analysis of publication numbers over time reveals the expansion of TCS&P secondary studies. **RQ 1.3:**_Which are the key publishing journals for TCS&P secondary studies?_  
Secondary texts are generally larger than the primary studies and involve a different research approach from those who propose new ideas. Therefore, not all conferences and journals support the publication of secondary studies. The answer to this RQ will provide possible publication targets for researchers working on secondary texts in the future. RQ 2. To study the characteristics of secondary studies. **RQ 2.1:**_Which research approaches have been used in secondary studies?_  
Several researchers have applied multiple techniques for secondary reviews on the existing texts. Different guidelines for different procedures have been presented [6; 19]. We categorized the research approaches for performing secondary studies into three types: (1) systematic literature reviews, (2) mappings, and (3) reviews/surveys. Analyzing which texts use which approach and how these are distributed over time will help answer the RQ. **RQ 2.2:**_What are the focus and the range of years covered in the secondary studies?_  
The analysis of the range of years of publication of the selected primary studies is an indicator of the length of coverage of secondary studies. It provides an insight into the variety of primary studies considered in the analysis. Surveys performed over similar ranges should have included similar texts that are related to the surveyed topic. It also helps future researchers search for primary studies that lie outside the already searched ranges. **RQ 2.3:**_How many texts form the basis of research for the selected secondary studies?_  
The extent of studies can also be judged depending on the number of chosen primary studies for conducting the survey. The number of primary studies chosen can vary widely for similar survey topics depending on the selected research questions. However, the number of mappings should be comparable for surveys on similar topics conducted for primary studies chosen from the same range of years. RQ 3. How have the secondary studies benefitted from the existing tools and tests? **RQ 3.1:**_How statistical tests been used in the secondary studies?_  
Comparisons and analysis of data in a secondary study may have used specific statistical tests. **RQ 3.2:**_Which tools have been used by the secondary studies?_ Our study analyzes the use of tools available for research purposes. RQ 4. How can the quality of secondary studies be compared? **RQ 4.1:**_How have the research questions been used in the secondary studies?_  
Research questions form the real basis of any survey, review, or mapping to be conducted. The analysis of the number and quality of research questions and whether they have been answered is part of our analysis. This will help in determining the quality of conclusions of the secondary studies.