Kickstart Guide to Literature Reviews

“Don’t reinvent the wheel; just realign it.”—Anthony J. D’Angelo

When starting your MSc thesis, especially one tied to a company project, it’s critical to frame the problem accurately and comprehensively. This means doing a thorough literature review to understand what’s already out there and find the gaps your work will fill. For a strong thesis, you need to describe the problem precisely, grounded in the latest research. The company might want you to build a tool, which is great, but you also have to prove you can frame, formally model, and solve a challenging problem. That’s exactly what your literature review does: it sets up the problem and shows why your work matters.

The Wall and the Brick

Think of the literature review as the foundation of your research, much like a wall built from academic papers. In the introduction, you identify a gap in this wall, highlighting where existing literature falls short. Your methodology then introduces the ‘brick’ that fills this gap. While it’s common to hint at this solution in the literature review, detailed information about the ‘brick’ should be reserved for the methodology section. This structure ensures your research both acknowledges the existing academic landscape and clearly delineates your contribution to it.

Literature Review vs. Literature Overview

A common mistake is conflating literature reviews with literature overviews. Here are some key differences:

  • The literature review is a critical analysis of existing research, summarizing and synthesizing findings to identify gaps and establish the context for your study.
  • Literature overviews are descriptive summaries of existing research, providing a broad understanding of the topic without necessarily identifying gaps or offering critical evaluations.

If you find yourself repeating what has already been stated in other reviews or textbooks, you are likely writing an overview rather than a literature review. Instead, focus on synthesizing existing research and identifying gaps that your study will address.

Research Gaps

Research gaps refer to areas or topics within a field of study that have not been adequately addressed or explored in existing research. Identifying research gaps is essential for advancing knowledge, developing new theories, and guiding future research efforts. By pinpointing areas where further investigation is needed, researchers can contribute to the growth and development of their field. Research gaps can arise from various sources, including theoretical, methodological, empirical, conceptual, temporal, spatial, and literature-related factors (see Table 1). It is easier to justify the importance of your research when you can clearly articulate the gaps in the existing literature that your study aims to address. Addressing these gaps requires a systematic approach that involves conducting a thorough literature review, critically evaluating existing research, and designing studies to fill the identified gaps. By addressing research gaps, researchers can make meaningful contributions to their field and advance the frontiers of knowledge.

Table 1: Definition of research gaps by type, examples, and strategies to address them.
Type Definition Examples How to Address
Theoretical Discrepancy between existing theories or models and observed phenomena Lack of studies examining the relationship between X and Y Conduct further research to test existing theories or develop new theoretical frameworks
Methodological Insufficiency or inadequacy in the methods used to investigate a research question Absence of studies utilizing qualitative methods in the field Review and refine research methodologies, consider alternative approaches, or combine methods to address limitations
Empirical Missing data or evidence needed to fully understand or explain a phenomenon Limited research on the long-term effects of treatment X Gather additional data through experiments, surveys, or longitudinal studies to fill gaps in knowledge
Conceptual Lack of clarity or consensus regarding key concepts or definitions in the field Variation in definitions of “success” across studies Clarify definitions through consensus-building efforts, standardization of terms, or development of clear conceptual frameworks
Temporal Lack of research over a certain period, leaving a discontinuity in understanding Sparse studies examining the impact of recent technological advancements Conduct studies to address current gaps and ensure research keeps pace with the latest developments in the field
Spatial Absence of research in specific geographical areas, limiting generalizability Few studies exploring the cultural differences in consumer behavior across regions Expand research efforts to include underrepresented geographical areas, ensuring a more comprehensive understanding of the phenomenon
Literature Failure to address existing knowledge gaps or build upon prior research adequately Neglecting to consider recent advancements in the literature when designing a study Conduct a thorough literature review to identify existing gaps and build upon prior research findings to contribute to the advancement of knowledge

Useful Tools

To help make your literature review process more efficient, consider using the following tools:

  • Explore literature related to your problem using Research Rabbit (best) or Connected Papers. These tools allow you to search for papers, create a network of related research, and discover new papers based on your interests.
  • Use Google Scholar to find academic papers, theses, books, and conference papers. It provides a broad search of scholarly literature across various disciplines.
  • Manage your references (e.g., papers, reports, websites) using Zotero (Research Rabbit can send papers directly to Zotero).

Parts of a Literature Review

In the following sections, we will highlight how key “moves” of the literature review are approached in existing literature. The excerpts provided are examples to help you implement these moves in your own literature review.

Scoping the Literature Review

Scope your literature review by focusing on specific aspects of the problem you are addressing. This helps narrow down the vast amount of literature to what is most relevant to your research. For example, you might focus on specific methodologies, algorithms, or applications within your field:

  • “The literature survey below will pay special attention to how the above-mentioned two central issues, the solution of the pricing problem in BCP algorithms and the solution of the interdependence problem in (local search) heuristics, are addressed. Other potentially promising ways for solving VRPMSs and their potential advantages and drawbacks will nevertheless be outlined.”
  • “This section provides an overview of various VRP modelling methodologies supported by data analytics and machine learning. In particular, we focus on modelling techniques for handling uncertain, incomplete, imprecise, or ambiguous data in VRPs, including stochastic programming, robust optimisation, chance-constrained programming, and data forecasting.”

Referring to Other Literature Reviews

You can refer to other literature reviews to provide context or background for your work. You do not need to repeat what has already been said. Instead, refer to existing reviews and focus on specific aspects relevant to your research. For example:

  • “The readers may refer to Elshaer and Awad (2020) for a comprehensive review of metaheuristics for VRP. This review focuses on machine learning-assisted VRP algorithms, and Section 4 discusses all relevant papers.”
  • “For a comprehensive review of robust optimisation, we refer interested readers to Bertsimas, Brown, and Caramanis (2010).”
  • “A good overview of such algorithms is provided by Molenbruch et al. (2017), who note that ‘in the standard problem, operational costs are minimized, subject to full demand satisfaction and service level requirements,’ closely relating to our study presented below.”
  • “Details on methods used to operationalize this controller have been extensively documented in several publications (Oh et al., 2020a; Nahmias-Biran et al., 2019; Basu et al., 2018), to which we refer interested readers.”
  • “The synthetic population for 2030 (6.7 million individuals) was generated using a Bayesian approach (Sun and Erath, 2015) based on socio-economic data, land-use data, and relevant control totals (see also Zhu and Ferreira, 2014, for more details on the population synthesis).”
  • “The calibration and validation also included matching simulated outputs to observed screen-line counts, public transit smart card data, and network travel times (for more details on the model calibration, readers are referred to Oh et al., 2020a).”
  • The presentation of the material assumes familiarity with vehicle routing problems (capacitated VRP, VRP with time windows VRPTW, pickup-and-delivery problem with time windows, capacitated arc routing problem, dial-a-ride problem, etc.) and with the standard modeling and exact and heuristic solution methodologies (mixed-integer programming, branch/cut/price, local/neighborhood search, metaheuristics). If this is not the case, the reader is referred to Toth and Vigo (2002); Golden, Raghavan, and Wasil (2008); Desaulniers, Desrosiers, and Solomon (2005); Funke, Grünert, and Irnich (2005); Røpke (2005); and Gendreau and Potvin (2010).
  • For more information on the split delivery VRP or pickup-and-delivery problem (PDP), the reader is referred to Hooker and Natraj (1995); Chen, Golden, and Wasil (2007); Archetti and Speranza (2008); Nowak, Ergun, and White (2008); Schönberger et al. (2009); Desaulniers (2010); Derigs, Li, and Vogel (2010); and Hennig (2010).

Literature Review Table

To effectively summarize the literature, consider creating a table categorizing existing research. This table should include key characteristics of each variant, relevant papers, and methods used. Readers appreciate this structured approach, as it allows quick comprehension of existing research.

To ensure your table is useful, search for similar tables in existing literature relevant to your topic. Identify key characteristics typically relevant to your field, which can then become columns or sections in your table.

Regardless of the specific characteristics chosen:

  • Ensure the table is clear and concise, allowing easy comparison of studies. If the table becomes too large, split it into multiple tables (e.g., one per variant category).
  • Explain the table in the text before presenting it, clarifying its purpose and interpretation. Each column and column value should be clearly defined and explained. Refer to previous explanations when appropriate.
  • Clearly state the reasons for including each paper in the table. Readers should understand why specific papers were chosen and how they contribute to overall topic understanding.
  • Make the table self-contained and understandable without referencing back to the text. Include all necessary information within the table itself. Abbreviations used in the table should be defined:
    • In the table header (e.g., your header could be “(D)ynamic/(S)tatic” with values as “D” or “S”).
    • In a footnote below the table.
    • In the caption of the table.
  • Add a final row to the table titled “This Thesis”/“Current Study”/“This Paper” to clearly indicate how your work fits into the existing literature.
  • The first column should be the author(s) and year of publication (\citet in LaTeX).
  • Order papers to easily identify key characteristics quickly. Papers discussing the same variant as your thesis and those closer to your methodology should be grouped together near your thesis at the bottom of the table.
  • Cite all papers included in the table within the text beforehand. This ensures readers are familiar with the papers and can refer to them for detailed information.

Tip: A good example of a concise literature review table can be found in Ulmer et al. (2018), Offline–Online Approximate Dynamic Programming for Dynamic Vehicle Routing with Stochastic Requests, Transportation Science, 53(1):185-202.

Concluding the Review

End your review with a concise summary clearly stating your research variant, emphasizing your contribution, and positioning it within existing literature:

“In this study, we specifically focus on the Dynamic Vehicle Routing Problem with Time Windows (DVRPTW). Our research addresses the integration of real-time stochastic demand forecasting with robust optimisation techniques.”

Examples of Literature Reviews

References