Types of literature review

Consideration of prior, relevant literature is essential for all research disciplines and all research projects. When reading an article, in­dependent of discipline, the author begins by describing previous re­search to map and assess the research area to motivate the aim of the study and justify the research question and hypotheses. This is generally referred to as the “literature review,” “theoretical framework,” or “re­search background.” However, for a literature review to become a proper research methodology, as with any other research, follow proper steps need to be followed and action taken to ensure the review is ac­curate, precise, and trustworthy. As with all research, the value of an academic review depends on what was done, what was found, and the clarity of reporting (Moher et al., 2009). Depending on the purpose of the review, the researcher can use a number of strategies, standards, and guidelines developed especially for conducting a literature review. Then, when should a literature review be used as a research method?

For a number of research questions, a literature review may be the best methodological tool to provide answers. For example, reviews are useful when the researcher wants to evaluate theory or evidence in a
certain area or to examine the validity or accuracy of a certain theory or competing theories (Tranfield et al., 2003). This approach can be narrow, such as investigating the effect of or relationship between two specific variables, or it can be broader, such as exploring the collective evidence in a certain research area. In addition, literature reviews are useful when the aim is to provide an overview of a certain issue or research problem. Typically, this type of literature review is conducted to evaluate the state of knowledge on a particular topic. It can be used, for example, to create research agendas, identify gaps in research, or simply discuss a particular matter. Literature reviews can also be useful if the aim is to engage in theory development (Baumeister & Leary, 1997; Torraco, 2005). In these cases, a literature review provides the basis for building a new conceptual model or theory, and it can be valuable when aiming to map the development of a particular research field over time. However, it is important to note that depending on the goal of the literature review, the method that should be used will vary.

1. Different approaches to conducting a literature review

As mentioned previously, there are a number of existing guidelines for literature reviews. Depending on the methodology needed to achieve the purpose of the review, all types can be helpful and appro­priate to reach a specific goal (for examples, please see Table 1). These approaches can be qualitative, quantitative, or have a mixed design depending on the phase of the review. In the following, three broad types of methods commonly used will be described, as summarized in Table 2. The broad types that will be presented and discussed include the systematic review, the semi-systematic review, and the integrative review. Under the right circumstances, all of these review strategies can be of significant help to answer a particular research question. How­ever, it should be noted that there are many other forms of literature reviews, and elements from different approaches are often combined. As these approaches are quite wide, it should be noted that they might require further adaptation for a particular research project.

1.1. Systematic literature review

What is it and when should we use it? Systematic reviews have fore­most been developed within medical science as a way to synthesize research findings in a systematic, transparent, and reproducible way and have been referred to as the gold standard among reviews (Davis et al., 2014). Despite all the advantages of this method, its use has not been overly prevalent in business research, but it is increasing (e.g., Snyder, Witell, Gustafsson, Fombelle, & Kristensson, 2016; Verlegh & Steenkamp, 1999; Witell, Snyder, Gustafsson, Fombelle, & Kristensson, 2016). A systematic review can be explained as a research method and process for identifying and critically appraising relevant research, as well as for collecting and analyzing data from said research (Liberati et al., 2009). The aim of a systematic review is to identify all empirical evidence that fits the pre-specified inclusion criteria to answer a par­ticular research question or hypothesis. By using explicit and systematic methods when reviewing articles and all available evidence, bias can be minimized, thus providing reliable findings from which conclusions can be drawn and decisions made (Moher et al., 2009).

What type of analysis can be conducted? Often, but not always, sta­tistical methods, such as the meta-analysis, are used to integrate the results of the included studies. A meta-analysis is a statistical method of combining results from different studies to weigh and compare and to identify patterns, disagreements, or relationships that appear in the context of multiple studies on the same topic (Davis et al., 2014). With the meta-analysis approach, each primary study is abstracted and coded, and findings are subsequently transformed into a common me­tric to calculate an overall effect size (Glass, 1976). However, to be able to perform a meta-analysis, the included studies must share statistical measures (effect size) to compare results (DerSimonian & Laird, 1986). Therefore, it is challenging to perform a meta-analysis on studies with different methodological approaches (Tranfield et al., 2003). Even though the systematic review method was developed in medical sci­ence, attempts have been made create guidelines within the social sciences (Davis et al., 2014; Palmatier et al., 2018; Tranfield et al., 2003). In addition, there are several published meta-analyses in higher- ranked business journals (Carrillat, Legoux, & Hadida, 2018; Chang & Taylor, 2016). However, in these areas, which not are restricted to randomized controlled trials, a major challenge lies in assessing the quality of research findings. As a result, more qualitative approaches have been developed to assess the quality and strength of findings from different types of studies and to compare results (Greenhalgh, Robert, Macfarlane, Bate, & Kyriakidou, 2004). This is often referred to as a qualitative systematic review, which can be described as a method of comparing findings from qualitative studies (Grant & Booth, 2009). That is, a strict systematic review process is used to collect articles, and then a qualitative approach is used to assess them.

What is a potential contribution from a systematic review? There are several advantages and potential contributions of conducting a sys­tematic review. For example, we can determine whether an effect is constant across studies and discover what future studies are required to be conducted to demonstrate the effect. Techniques can also be used to discover which study-level or sample characteristics have an effect on the phenomenon being studied, such as whether studies conducted in one cultural context show significantly different results from those conducted in other cultural contexts (Davis et al., 2014).

1.2. Semi-systematic review

What is it and how should it be used? The semi-systematic or narrative review approach is designed for topics that have been conceptualized differently and studied by various groups of researchers within diverse disciplines and that hinder a full systematic review process (Wong et al., 2013). That is, to review every single article that could be relevant to
the topic is simply not possible, so a different strategy must be devel­oped. There are several examples of articles using this approach pub­lished in business journals (e.g., McColl-Kennedy et al., 2017). Besides the aim of overviewing a topic, a semi-systematic review often looks at how research within a selected field has progressed over time or how a topic has developed across research traditions. In general, the review seeks to identify and understand all potentially relevant research tra­ditions that have implications for the studied topic and to synthesize these using meta-narratives instead of by measuring effect size (Wong et al., 2013). This provides an understanding of complex areas. How­ever, while covering broad topics and different types of studies, this approach holds that the research process should be transparent and should have a developed research strategy that enables readers to assess whether the arguments for the judgments made were reasonable, both for the chosen topic and from a methodological perspective.

What type of analysis can be conducted? A number of methods can be used to analyze and synthesize findings from a semi-systematic review. These methods often have similarities to approaches used in qualitative research in general. For example, a thematic or content analysis is a commonly used technique and can be broadly defined as a method for identifying, analyzing, and reporting patterns in the form of themes within a text (Braun & Clarke, 2006). Although this type of review is usually followed by a qualitative analysis, there are exceptions. For example, Borman and Dowling (2008) used a semi-structured method of collecting literature but combined it with a statistical meta-analysis approach.

What is a potential contribution from a semi-systematic review? This type of analysis can be useful for detecting themes, theoretical per­spectives, or common issues within a specific research discipline or methodology or for identifying components of a theoretical concept (Ward, House, & Hamer, 2009). A potential contribution could be, for example, the ability to map a field of research, synthesize the state of knowledge, and create an agenda for further research or the ability to provide an historical overview or timeline of a specific topic.

1.3. Integrative review

What is it and when should it be used? Closely related to the semi­structured review approach is the integrative or critical review ap­proach. In comparison to the semi-structured review, an integrative review usually has a different purpose, with the aim to assess, critique, and synthesize the literature on a research topic in a way that enables new theoretical frameworks and perspectives to emerge (Torraco, 2005). Although rare, examples of this type of review can be identified in the business literature (e.g., Covington, 2000; Gross, 1998; Mazumdar, Raj, & Sinha, 2005). Most integrative literature reviews are intended to address mature topics or new, emerging topics. In the case of mature topics, the purpose of using an integrative review method is to overview the knowledge base, to critically review and potentially re­conceptualize, and to expand on the theoretical foundation of the specific topic as it develops. For newly emerging topics, the purpose is rather to create initial or preliminary conceptualizations and theoretical models, rather than review old models. This type of review often re­quires a more creative collection of data, as the purpose is usually not to cover all articles ever published on the topic but rather to combine perspectives and insights from different fields or research traditions.

Table 3

Important questions to consider in each step of the review.

Phase 1: design

• Is this review needed and what is the contribution of conducting this review?
• What is the potential audience of this review?
• What is the specific purpose and research question(s) this review will be addressing?
• What is an appropriate method to use of this review’s specific purpose?
• What is the search strategy for this specific review? (including search terms, databases, inclusion and exclusion criteria etc.)

Phase 2: conduct

• Does the search plan developed in phase one work to produce an appropriate sample or does it need adjustment?
• What is the practical plan for selecting articles?
• How will the search process and selection be documented?
• How will the quality of the search process and selection be assessed?

Phase 3: analysis

• What type of information needs to be abstracted to fulfill the purpose of the specific review?
• What type of information is needed to conduct the specific analysis?
• How will reviewers be trained to ensure the quality of this process?
• How will this process be documented and reported?

Phase 4: structuring and writing the review

• Are the motivation and the need for this review clearly communicated?
• What standards of reporting are appropriate for this specific review?
• What information needs to be included in the review?
• Is the level of information provided enough and appropriate to allow for transparency so readers can judge the quality of the review?
• The results clearly presented and explained?
• Is the contribution of the review clearly communicated?

What type of analysis can be used? The data analysis part of an in­tegrative or critical review is not particularly developed according to a specific standard (Whittemore & Knafl, 2005). However, while there is no strict standard, the general aim of a data analysis in an integrative review is to critically analyze and examine the literature and the main ideas and relationships of an issue. It should be noted that this requires researchers to have advanced skills, such as superior conceptual thinking (MacInnis, 2011) at the same time as being transparent and document the process of analysis.

What is a potential contribution from an integrative review? An in­tegrative review method should result in the advancement of knowl­edge and theoretical frameworks, rather than in a simply overview or description of a research area. That is, it should not be descriptive or historical but should preferably generate a new conceptual framework or theory. Although an integrative review can be conducted in a number of ways, researchers are still expected to follow accepted conventions for reporting on how the study was conducted (Torraco, 2005). That is, how the integrative was done and how articles were selected must be transparent. However, a note of caution. While well- conducted integrative reviews can make a valid and strong contribution to its field of research, more often than the opposite, they either lack transparency or true integration of research. Frequently, reviews la­beled as integrative are simply summaries of studies and not truly in­tegrative.

2. How to decide on what approach to use

While it can be challenging to determine what approach is most appropriate for a specific type of review, the research question and specific purpose of the review always determine the right strategy to use. While the systematic review is perhaps the most accurate and rigorous approach to collect articles, because there is certainty that all relevant data have been covered, this approach requires a narrow re­search question, and it might not be feasible or even suitable for all types of projects. This is where the semi-systematic review can be useful, but this approach is also more problematic and as it has fewer clear steps to follow. While the methodology for systematic reviews is straightforward and follows highly strict rules and standards (Liberati et al., 2009), the semi-systematic review process requires more devel­opment and tailoring to the specific project (Wong et al., 2013). Often, researchers need to develop their own standards and a detailed plan to ensure the appropriate literature is accurately covered to be able to answer their research question and be transparent about the process. However, if done properly, this can be a highly effective way of cov­ering more areas and broader topics than a systematic review can handle. In addition, when it comes to the integrative review, it becomes even more demanding, which puts more responsibility on and requires more skills of the researchers, as there are even fewer standards and guidelines on which to rely for developing a strategy (Torraco, 2005). This leads to the notion that an integrative review approach might not be advisable to use, and if compared to the systematic review, it might not hold the same amount of rigor. However, if successfully conducting a truly integrative review and contributing with a new conceptual model or theory, the reward can be significant (MacInnis, 2011).

Source: Hannah Snyder (2019), “Literature review as a research methodology: An overview and guidelines”, Journal of Business Research, Volume 104, Pages 333-339, https://doi.org/10.1016/j.jbusres.2019.07.039