Chapter 3: How to Write the Introduction and Literature Review

Finding Empirical Studies for the Literature Review

The first step to write the Introduction and Literature Review is to locate peer-reviewed journal articles of empirical studies^[1]. In general, students are required to review about 15 to 20 empirical studies published in peer-reviewed journals within 10 years from the date of the literature review of the graduate research paper. This is the first challenge many students face in terms of understanding and finding “empirical studies.” “Empirical” studies mean studies that analyze data about social phenomena and human behavior by means of direct and/or indirect observation as “empirical” indicates experience. We conduct research to understand or explain social phenomena or human behavior of our interest by collecting observable data from a certain group of people since we can’t collect data from all people of our interest. Thus empirical studies should include the Methods section to explain how the data has been collected and the Results section to report the study findings with analysis on observable data collected.

A simple way to find empirical studies is to check the Abstract of the published articles. As shown in Figure 3-1, the Abstract contains Methods explaining data and the sample size, and Results reporting the study findings. As mentioned previously in Chapter 2, abstracts in most studies have the same components in the same order including a few sentences of the Background information, Methods, Results/Findings, and Discussion/Implications. Empirical studies published in peer-reviewed journals should provide the number of people the study collected data, which is a sample size and some additional information about data collection or sample in Methods and the study findings in Results. By checking those information in abstracts, we can identify whether the articles are empirical or not^[2].  

The most popular website to search and find scholarly articles is Google Scholar. Students can use Google Scholar with and without the University’s credentials. When using Google Scholar without the University’s credentials, we can access only full-text articles that are open to the general public. When using Google Scholar with the University’s credentials (via the library website), we can access full-text articles the University subscribes. Students can use databases that the University provides in various discipline. For example, through the institution’s library website students have access to specialized databases such as Social Work Abstract (EBSCO), Medline, APA PsycInfo (EBSCO) for psychology, ProQuest, ERIC for education (EBSCO), and other EBSCO sites depending on the academic areas. There are also freely-available databases such as PubMed (National Institutes of Health) and PTSDPubs (National Center for PTSD), which can help with identifying studies. Librarians can help you determine the best places to search based on your topic and research questions.

Although students know where to go to search empirical studies conducted in their study topic area, they may still struggle locating articles. This challenge is due to the lack of understanding of search terms for the research topic. To locate empirical articles that examined similar topics, students should think about the study population, dependent variable, and primary independent variables. The study population can be specified as children, adolescents, young adults, adults, older adults, LGBTQ+, immigrants, females, veterans, and more. Sometimes academic terms are different from the words we use in general. For example, studies on the LGBTQ+ population can be found with the term “sexual minority,” social media can be found with “digital media,” “online communication,” or “social network,” adverse childhood experiences with “childhood adversities,” “child abuse,” or “family/household dysfunction.” One way to understand the academic terms is to check keywords in the articles that we found usually presented after or next to the Abstract of the article as shown in Figure 3-1. In addition, library databases often have a Subject Term list or Thesaurus, which consists of official terms for each article.

Figure 3-1. Keywords Presented in the Article

Figure 3-2 Finding Articles from Google Scholar 

Upon finding the first article on Google Scholar, we can find more articles with articles that cited the first article we find by clicking the number under the title of the article that indicates Cited by 29 as yellow-highlighted in Figure 3-2. The highlighted part in Figure 3-2 shows the number of articles that cited the first article we find. When we click the highlighted part, Google Scholar provides articles that cited the first article we just found. Those articles are related to our study topic and are more recently published as they cited the first article after it was published. We can search the most current articles by setting a limit in the years of publication in Google Scholar as displayed on the left side of Figure 3-2.  

We can find more articles related to our study topic by checking the References section of the articles we find. References include all scholarly articles and books that were cited for the article and are related to our study topic. However, the articles in the References section are published earlier than the article we found and may be too old to use for our current study. Before we compile articles for References, it will be beneficial to consult with a liaison librarian to get more information on keywords and search terms for our topic and databases available at the university.

In addition, it will be helpful in saving the correct citation format of the articles from the Google search engine by clicking “Cite” next to “Cited by” as shown in Figure 3-1 if the article is to be used for the literature review. If we click “Cite”, it shows different types of citation formats of the article such as APA, Chicago, Harvard, and others. You can save the APA citation format in your References section of the paper. Citation management software, such as Zotero, Mendeley, or Endnote Click, can also save time and stress by saving and formatting citations.

Components of the Introduction

The Introduction section gives an overview of the study topic including, both the IV and the DV. Key differences between the Introduction and the Literature Review sections are the intensity of information in that Introduction provides an overview of the study on why the study topic is important and worthy of being researched by describing the scope of the topic/issue and its impacts on humans subjects in the social environment. Common mistakes that students make when they write their Introduction section are they write their personal ideas and thoughts about why the study topic is important such as “I think that child maltreatment is important to study as we will become social workers working with children…….,” “intimate partner violence is important to me because I want to work for them…….” These types of writings are inappropriate not only for a graduate research paper/thesis but also for any type of research paper because a research paper should be written in a way to highlight research findings, which are evidence.

Research papers are different from essay or reflection papers that many students write while studying in undergraduate and graduate programs. Essay and reflection papers contain personal experiences and reflectional thoughts on a topic while research papers should contain scientific evidence, which is research findings produced by systemic research conducted with scientific research methods. In a research paper, almost every sentence should be written as being objective and evidence-based. This evidence is provided with citations of the research articles published in peer-reviewed journals to show that the points we attempt to make are not based on personal ideas, thoughts, and opinions, but based on evidence found, reviewed, and disseminated to the public through publication. Therefore, the importance of the study topic can be stated by emphasizing the scope of the topic/issue that shows how immense the topic is, and how impactful the topic is on the study population in general. We can convince the readers about the importance of the research topic by providing statistics of rates of occurrence, percentages, and prevalence examined or estimated by other research. For the Introduction, reports released by the local, U.S. governmental agencies (e.g., NIH, NIMH, or CDC), nationwide research institutes (e.g., Pew Research, Rand, or Urban Institute), or global agencies (e.g., agencies in the United Nations, Organization of Economic Cooperation and Development, or World Health Organizations) are good sources to cite for the scope of the topic. It is not recommended to cite statistics presented in non-profit organizations since most non-profit organizations also use the statistics generated by the published articles or the above sources^[3] unless the organizations are research agencies.  

Good examples to begin writing the Introduction section of a graduate thesis are the following presented in the Examples below. In Example 1, the study examined a relationship between social media use and depression. The authors began with the trends of depression rates and social media use over time. In Example 2, the study examined how adverse childhood experiences (ACEs) are associated with social media use. The authors provide the prevalence of ACEs in the Introduction. In Example 3, the study examined intimate partner violence and HIV. As for the Introduction, the authors provided the risk rate of HIV among females in diverse groups.

Example 1. “Prevalence rates of depressive symptoms among adolescents have increased substantially over the past decade (Twenge et al., 2019), coinciding with the rising popularity of social media sites (Anderson & Jiang, 2018).” (Nesi et al., 2022, p. 907)

Example 2. “Prevalence of ACEs is estimated to be as high as 60% in the United States (Bynum et al., 2010; Carlson et al., 2020; CDC, 2019) and worldwide (Carlson et al., 2020). With the advent of the COVID-19 pandemic in early 2020 and the following economic stress and instability within the United States, there has been an increase of stress in parenting (Brown et al., 2020), which may contribute to increased risk for ACEs (Bryant & Damian, 2020; Cuartas, 2020)” (Cao et al., 2023, p. e451).        

Example 3. “Compared with the general population of women of reproductive age, the relative risk of acquiring HIV is 30 times greater among female sex workers, 29 times greater among people who inject drugs, and 13 times greater among transgender people, and 20% of all new HIV infections are among adolescent girls and young women (UNAIDS, 2020).” (El-Bassel et al., 2022, p. 1).

When we conduct research, the study has at least two primary variables of dependent and independent variables (DV and IV) to examine how the IV affects the DV. Thus, we provide the scope of the issue for each of the main variables in similar patterns of writing. For example, the Introduction for a research topic of intimate partner violence and drinking provides the scope of the issue for both intimate partner violence and drinking.

In many cases, the study’s main focus is placed on the dependent variable, but its focus can be on an independent variable as well. Although the Introduction generally begins with the scope of the issue of the dependent variable, it can begin with the scope of the issue of the independent variable. In Example 1 above, depression is the study outcome variable, which is the study’s DV while social media use is the IV that affects the DV of depression. The authors began the prevalence of depression (DV first). In Example 2 above, the study examined whether adverse childhood experiences (ACEs) increase social media use wherein ACEs are the IV and social media use is the DV.  Authors began the prevalence of ACEs (IV first).  In Example 3, HIV is the DV, and intimate partner violence is the IV. The authors began with the risk of HIV in diverse female groups (DV first). Regardless of which variable it begins to describe, it is better to provide the scope of the issues for both topics of the variables to emphasize the importance of both issues because both dependent and independent variables are equally important to be researched.

The second part of the Introduction is to connect the IV with the DV. In other words, how the dependent variable of the study is affected by the independent variable(s) based on research findings published in peer-reviewed journals. Therefore, this part of the Introduction can be finalized or revisited after the Literature Review. The reason for selecting specific topics of the IV and the DV for research is that we assume and hypothesize the two variables to be related. If not, there is no reason to research these IV and DV. as they are likely to occur randomly by chance without any association. For example, adverse childhood experience and social media use were examined by the study in Example 2 above because the study conceived the idea that youth who have adverse childhood experiences are more likely to use social media.

When we begin with DV first in Introduction, then we explain what factor(s) affect or lead to DV in the next such as social media increases depression (Example 1). When we begin with the IV first in Introduction, then we move to how the IV affects the DV  such as ACEs affect social media use (Example 2). The Introduction briefly provides how the IV links to the DV as a head-up. Contrary to the Literature Review which contains an extensive review of existing study findings on the relationship between the IV and the DV, the Introduction is briefly introducing the relationship between the IV and the DV reported by existing study findings with citation(s). The following are good examples for this part of the Introduction using the same studies presented in the Examples above.

Example 1. “Some prior work, including recent meta-analyses, suggests associations between frequent social media use and depressive symptoms (Keles et al., 2020; McCrae et al., 2017; Twenge et al., 2019)” (Nesi et al., 2022, p. 907).

Example 2. “Although numerous studies have documented the consequences of digital media use during childhood and adolescence, less is known about the underpinnings of the amount of time children spend on digital media. Emerging research, however, points to the household environment and caregivers as central to children’s digital media usage (Lauricella et al., 2014)” (Jackson et al., 2022, p. 462-463).

Example 3. “Women who experience intimate partner violence have a greater risk of HIV acquisition and limited access to HIV prevention, testing, treatment, and care (Siemieniuk et al., 2013).” (El-Bassel et al., 2022, p. 1).

In Example 1, the study examined social media use and depression. Thus the authors introduced the relationship between social media use and depression reported by existing studies that found a significant association with citations. In Example 2, the study examined adverse childhood experiences and social media use. The authors introduced existing study findings reporting that ACEs are related to social media use although limited studies have examined the relationship between the two variables. In Example 3, the study examined intimate partner violence and HIV. Thus, the authors introduced the relationship between intimate partner violence by stating that women with intimate partner violence have a greater risk of acquiring HIV with citations.

The last part of the Introduction straightforwardly describes the primary focus/objective/goal of the graduate research project as a closing statement of the Introduction section as shown in the examples below. In many published studies, Introduction and Literature Review were combined due to the page limits, and the Introduction is relatively short within a paragraph and the statement about the goal/aim of the study is often presented at the end of the Literature Review. For a graduate research thesis/paper, one or two pages of the Introduction are appropriate. In case the graduate research adopts a conceptual framework or theoretical framework, it is better to mention what theory/perspective/framework the graduate research project adopts.

Example 1. “This work by using contemporary and nationally representative data from the 2018 National Survey of Children’s Health (NSCH) is to provide the first study of the association between ACEs and digital media use among children and adolescents in the U.S.” (Jackson et al., 2022, p. 463).

Example 2. “The current study examined bidirectional associations between adolescents’ emotional responses to social media experiences and depressive symptoms, and explored gender differences in these processes” (Nesi et al., 2021, p. 908).

Writing the Literature Review

The Literature Review section is different from the Introduction. The Introduction provides a brief background of the study topic to remind the readers of the significance of the study topic and emphasizes the importance of conducting the study and the connection of the IV with the DV. However, the primary purpose of the literature review is to understand existing study findings on the study topic. The literature review solely focuses on the existing study findings on the relationship between the study’s IV and DV in terms of the direction and the statistical significance of the relationship between the IV and the DV, indicating the IV significantly increases or decreases the DV, or does not affect (is not related to) the DV.

Understanding existing study findings is critical before conducting our research since it helps us understand what studies have or have not been conducted so far in the research topical area of our interest, and identify what research findings have been reported, what limitations of the existing studies still have, and what knowledge or methodological gaps among studies still exist. This understanding guides the development of the study hypotheses or the creation of a new study to fill the gaps, avoid limitations, or duplicate the same study to examine the accuracy of existing study findings (as one of the characteristics of science is replication). After understanding existing study findings on the relationship between the study’s IV and DV, gaps, and limitations of the existing studies, we can finalize our tentative research hypotheses.  

Content of the Literature Review

In general, students review about 15 to 20 empirical studies published in peer-reviewed journals for the literature review. It is somewhat difficult for students to achieve the primary purposes of the literature review stated above because it is not feasible to understand comprehensively what has been done, what findings have been reported, what their limitations are, and what types of research gaps of these existing studies have been presented with just 15 to 20 empirical studies. Although it is recommended to present gaps and limitations of the literature they reviewed, a student’s paper is generally expected not to state their understanding of the academic field related to the study topic in a decisive or comprehensive term, but to present their understanding of empirical study findings and their limitations within the limit of 15 to 20 empirical research articles they reviewed.

In terms of understanding empirical study findings, students need to catch the key findings of each study about the relationship of the study’s IV and DV with the key information of the research methods that the research utilized such as research design (i.e., cross-sectional or longitudinal design, quantitative or qualitative design, what types of quantitative or qualitative design, etc.), sampling methods (i.e., the study population, sample size, probability or non-probability sampling, what type of probability or non-probability sampling, etc.).

When writing the Literature Review, it is easier to organize the literature review around the relationship with key variables, the study’s IV and DV, or a theoretical framework if we have one. The content of the Literature Review depends on the number of key IVs as research findings on the relationship between each of the key IVs and DV should be reviewed in the Literature Review. Thus the Literature Review can have two parts if we have two key IVs: One part for reviewing study findings on relationships between one IV and DV and the other part for relationships between the other IV and DV. It is not necessary to write about every single article, but it is necessary to represent every major point of view in existing studies. For the writing purpose, we can make groups of articles by 1) Findings on directions of the relationship between the IV and the DV such as positive, negative, or no relationship between each IV and DV; 2) Findings based on research design such as cross-sectional or longitudinal design, quantitative or qualitative design, or types of qualitative or quantitative studies.

Example 1. “In fact, longitudinal studies have shown that individuals with ACEs tend to have less interpersonal social support than those without ACEs when they become adults (Sperry et al., 2013; Horan et al., 2015; Lagdon et al., 2021)” (Cao et al., 2022, p.2).

Example 2. “Emerging research, however, points to the household environment and caregivers as central to children’s digital media usage (Lauricella et al., 2016). For instance, compared with tweens in higher-income households, tweens in lower-income households spend about 1 hour and 50 additional minutes per day on digital media (5:49 vs 3:59), and teens in lower-income households spend about 1 hour and 43 additional minutes per day on screen media compared with teens in higher-income households (8:32 vs 6:49) (Rideout et al., 2019). Other studies, moreover, find that adverse experiences and trauma can escalate the problematic use of digital media in the form of Internet and mobile phone addiction (Grajewski et al., 2020; Li et al., 2020; Schimmenti et al., 2017; Wilke et al., 2021)” (Jackson et al., 2021, p.463).

Example 3. “Extensive research has shown that HIV and intimate partner violence are inexorably linked, particularly among these key populations of women (Campbell et al., 2008). Women who experience intimate partner violence have a greater risk of HIV acquisition and limited access to HIV prevention, testing, treatment, and care (Siemieniuk et al., 2013)” (El-Bassel et al., 2022, p.1).

The study in Example 1 above wrote key findings from longitudinal studies with multiple citations. This example study organized the literature review with findings based on research methods of longitudinal and cross-sectional studies. The study in Example 2 above provided the impact of specific adverse childhood experiences (IV) with the household environment, caregivers, and overall ACEs and trauma on social media use (DV). This is a good example worth our attention to specific variables of generic IV in diverse studies. Although ACEs are the key IV, each study can focus on specific variables of the ten types of ACEs depending on their data such as child abuse and neglect, sexual abuse, physical abuse, household dysfunction, household environment, and a relationship between parents and children. Among the studies that examined the same IV and DV in generic terms, specific variables can be different. Paying attention to the differences among studies makes the Literature Review more advanced. Example 3 shows the main points of the existing study findings based on the relationships between intimate partner violence (IV) and HIV (DV) with multiple citations.

The end of the Literature Review section should lead the reader back to our present study. Thus, the Current Study is presented at the end of the Literature or at the beginning of the Methods section with or without a separate heading.  In other words, the literature review is required to justify our study goals/aims by identifying what is not known about the study area or what to be further researched as our study aims will address this lack of knowledge or fill in this gap. We also provide definitions of primary terms and/or concepts at the beginning of the Literature Review when the terms are required to be defined in cases the definition helps understand or minimize confusion of the concepts and terms used in our study.

The Current Study

This section is to present our study goals/aims after existing study findings and gaps/limitations of the existing literature we reviewed and states the primary purpose of our study by presenting research questions/hypotheses as presented in the Examples below. Gaps/limitations of the existing literature can be presented in this section as well before stating our study purposes and hypotheses. Example studies below present the aims of the study after the literature review.

Example 1. “The aim for the present study was twofold. Firstly, we attempted to obtain a psychometrically sound factor solution of the MC-OWBS to be used in routine care for a cross-cultural detection of TGBs. Secondly, we investigated the hypothesis that there is an association between TGBs and depression, IPV, and perceived stress (sources of construct validity). Based on previous research, we expected a three- and four-factor solution based on content areas and processes to be difficult to replicate. We also expected that, once a robust factor structure was obtained, TGBs would be associated with more severe depressive symptoms, stress, and IPV.” (Rovira et al., 2022, p.3)

Example 2. “..... Motivated by this, we used data from 2 social media platforms to examine the web-based social networks of individuals reporting ACEs and discuss implications for public health.” (Cao et al., 2022, p.2)

Example 3. “Despite the plausibility of a connection between ACEs and digital media use, empirical examinations of this association are absent from the literature…… This study aims to expand on this work by using contemporary and nationally representative data from the 2018 National Survey of Children’s Health (NSCH) to provide the first study of the association between ACEs and digital media use among children and adolescents in the U.S.” (Jackson et al., 2022, p.463)