On Using Grey Literature and Google Scholar in Systematic Literature Reviews in Software Engineering

Affan Yasin,Wasif Afzal,Rubia Fatima,Muhammad Azhar,Lijie Wen,Richard Torkar

doi:10.1109/access.2020.2971712

Abstract

Context: The inclusion of grey literature (GL) is important to remove publication bias while gathering available evidence regarding a certain topic. The number of systematic literature reviews (SLRs) in Software Engineering (SE) is increasing but we do not know about the extent of GL usage in these SLRs. Moreover, Google Scholar is rapidly becoming a search engine of choice for many researchers but the extent to which it can find the primary studies is not known. Objective: This tertiary study is an attempt to i) measure the usage of GL in SLRs in SE. Furthermore this study proposes strategies for categorizing GL and a quality checklist to use for GL in future SLRs; ii) explore if it is feasible to use only Google Scholar for finding scholarly articles for academic research. Method: We have conducted a systematic mapping study to measure the extent of GL usage in SE SLRs as well as to measure the feasibility of finding primary studies using Google Scholar. Results and conclusions: a) Grey Literature: 76.09% SLRs (105 out of 138) in SE have included one or more GL studies as primary studies. Among total primary studies across all SLRs (6307), 582 are classified as GL, making the frequency of GL citing as 9.23%. The intensity of GL use indicate that each SLR contains 5 primary studies on average (total intensity of GL use being 5.54). The ranking of GL tells us that conference papers are the most used form 43.3% followed by technical reports 28.52%. Universities, research institutes, labs and scientific societies together make up 67.7% of GL used, indicating that these are useful sources for searching GL. We additionally propose strategies for categorizing GL and criteria for evaluating GL quality, which can become a basis for more detailed guidelines for including GL in future SLRs. b) Google Scholar Results: The results show that Google Scholar was able to retrieve 96% of primary studies of these SLRs. Most of the primary studies that were not found using Google Scholar were from grey sources.

Highlights

The Internet has become a vital channel for disseminating and accessing scientific literature for both the academic and industrial research needs
VALIDITY THREATS This study is conducted using the guidelines for performing systematic literature reviews (SLRs) [22], though on the scale of a systematic mapping study as we asked general questions
A validity threat is that we did not search in electronic databases other than ACM digital library, IEEE Xplore, Science Direct and Springer Link

Summary

Introduction

The Internet has become a vital channel for disseminating and accessing scientific literature for both the academic and industrial research needs. Everyone has comprehensive access to scientific literature repositories, which com-. The associate editor coordinating the review of this manuscript and approving it for publication was Resul Das. prise of both ‘‘white’’ and ‘‘grey’’ literature. The ‘‘grey’’ literature, as opposed to ‘‘white’’ literature, is non-peer reviewed scientific information that is not available using commercial information sources such as IEEE or ACM. A large number of software engineering researchers are undertaking systematic literature reviews (SLRs) to investigate empirical evidence in software engineering. The key reason to include grey literature during information synthesis is to minimize the risk of.

Objectives

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Results

Discussion

Conclusion