Review of Relevant Literature

Purpose of the Literature Review in Writing Course Papers

For most course papers, your instructor will expect you to review published information on the topic of your paper. Thus, these papers will require literature reviews although the literature you search for may be different. The search should include both periodicals and monographs. For some topics, you may primarily find your material in periodicals, whereas for other topics, you will derive most information from monographs and find little in periodicals. You may find it fruitful to search the Internet for research on some topics. However, document the source and validity of the Internet content you find.

Purpose of the Literature Review in Examining the Strength of the Evidence

The purpose of the literature review designed to examine the strength of the evidence is to identify all studies that provide evidence of a particular intervention, to critique the quality of each study, and to synthesize all of the studies providing evidence of the effectiveness of a particular intervention. It is also important to locate and include previous evidence-based papers that have examined the evidence of a particular intervention, because the conclusions of these authors are highly relevant. This type of literature review is described in greater detail in Chapter 27, Strategies for Promoting Evidence-Based Nursing Practice.

Purpose of the Literature Review in Quantitative Research

The review of literature in quantitative research directs the development and implementation of a study. The major literature review is conducted at the beginning of the research process, and a limited review is conducted during the generalization phase of the research report to integrate knowledge from the literature with new knowledge obtained from the study. The purpose of the literature review is similar for the different types of quantitative studies (descriptive, correlational, quasi-experimental, and experimental). Relevant sources are cited throughout a quantitative research report in the introduction, methods, results, and discussion sections. The introduction section uses relevant sources to summarize the background and significance of the research problem. The review of literature section includes both theoretical and empirical sources that document the current knowledge of the problem. The framework section is developed from the theoretical literature and sometimes from empirical literature, depending on the focus of the study. The methods section describes the design, sample, measurement methods, treatment, and data collection process of the planned study and is based on previous research. Thus, previous studies may be cited in the methods section. In the results section, the data are analyzed with knowledge of the results of previous studies. These studies and their findings should be identified at this point and cited. The discussion section of the research report provides conclusions that are a synthesis of the cited findings from previous research and those from the present study.

Purpose of the Literature Review in Qualitative Research

In qualitative research, the purpose and timing of the literature review vary based on the type of study to be conducted. Some phenomenologists believe the literature should not be reviewed until after the data have been collected and analyzed so that the literature will not influence the researcher’s openness (Munhall, 2006). For example, if a researcher decided to describe the phenomenon of dying, the review of literature would include Kubler-Ross’s (1969) five stages of grieving. Knowing the details of these stages early on could influence the way the researcher views the phenomenon during data collection and analysis. However, after data analysis, the information from the literature can be compared with findings from the present study to determine similarities and differences. The findings can then be combined to reflect the current knowledge of the phenomenon.

In grounded theory research, a minimal review of relevant studies is done at the beginning of the research process. This review is only a means of making the researcher aware of what studies have been conducted, but the information from these studies is not used to direct data collection or theory development for the current study. The researcher primarily uses the literature to explain, support, and extend the theory generated in the study (Munhall, 2006).

Ethnographic research is reviewed in a manner similar to that used for quantitative research. The literature is reviewed early in the research process to provide a general understanding of the variables to be examined in a selected culture. The literature is usually theoretical because few studies have typically been conducted in the area of interest. From these sources, the researcher develops a framework for examining complex human situations in the selected culture (Munhall, 2006). The literature review also provides a background for conducting the study and interpreting the findings.

In historical research, an initial literature review is conducted to select a research topic and to develop research questions. Then the investigator develops an inventory of sources, locates these sources, and examines them; thus, the literature is a major source of data in historical research. Because historical research requires an extensive review of literature that is sometimes difficult to locate, the researcher can spend months and even years locating and examining sources. The investigator then analyzes and organizes the literature into a report that explains how an identified phenomenon has evolved over a particular time period (Munhall, 2006).

• What is known about your topic?

• What is the chronology of the development of knowledge about your topic? Knowledge related to an empirical study includes theories and empirical studies.

• What research evidence is lacking, inconclusive, contradictory, or too limited

• Is there a consensus or significant debate on issues? What are the various positions?

• What directions for your study are indicated by the work of other researchers?

• What are the characteristics of the key concepts or variables in relevant theories or previous studies?

• What are the relationships among the key concepts or variables in relevant theories or previous studies?

• What are the existing theories in the field of study?

• Where are the inconsistencies or other shortcomings in the knowledge base?

• What views need to be (further) tested?

• Why should a problem be (further) studied?

• What contribution can the present paper be expected to make?

• What approaches, designs, or methods of previous studies seem unsatisfactory?

Time Frame for a Literature Review

The time required to review the literature is influenced by the problem studied, sources available, and goals of the reviewer. There is no set length of time for reviewing the literature, but there are guidelines for directing the review process. The narrower the focus of the topic, the less time will be required to review the literature. The difficulty you experience identifying and locating sources and the number of sources to be located also influence the time involved, as will the intensity of effort. Only through experience does one become knowledgeable about the time frame for a literature review. Novice reviewers will require more time to find the needed literature than an experienced searcher, and the novice frequently underestimates the time needed for the review. A time estimation device for novice searchers, as recommended by at least one librarian, is for the searcher to make a good “reasonable” time estimation and then multiply this number by four. This longer estimate is often more realistic. As both time judgment and searching skills are refined the need to use this expanded estimate reduces.

If researchers attempted to read every source that is somewhat related to a selected problem, they would be well read but would probably never complete their search. Some individuals, even after a thorough literature review, continue to believe that they do not know enough about their area of interest, so they persist in their review; however, this ultimately becomes an excuse for not progressing with their work. The opposite of this situation is the individual who wants to move rapidly through the review of literature to reach the “important part” of their work. In both situations, the person has not been able to set realistic goals for conducting the literature review.

Students repeatedly ask, “How many articles should I have? How far back in years should I go to find relevant information?” The answer to both those questions is an emphatic “It depends.” Course faculty for masters courses commonly require that you obtain full text articles of all studies (covering all variables in the proposed study) for the previous ten years plus the classic studies conducted in the field of research. Doctoral students are expected to conduct a more extensive review for course papers. If you are writing a research proposal for a thesis or dissertation, the literature required will be extensive. You need to locate the key papers in the field of interest. If you are searching for research, you need to identify the landmark or seminal studies done. Seminal studies are the first studies that prompted the initiation of the field of research. Landmark studies mark an important stage of development or a turning point in the field of research. Beyea & Nicoll (1998) provide some good advice about knowing when you have sufficient sources:

Sources Included in a Literature Review

Two types of literature are cited in the review of literature for research: theoretical and empirical. Theoretical literature consists of concept analyses, models, theories, and conceptual frameworks that support a selected research problem and purpose. Theoretical sources can be found in serials, periodicals, and monographs. Serials are published over time or may be in multiple volumes but do not necessarily have a predictable publication date. Periodicals are subsets of serials with predictable publication dates, such as journals, which are published over time and are numbered sequentially for the years published. This sequential numbering is seen in the year, volume, issue, and page numbering of a journal. Monographs, such as books, booklets of conference proceedings, or pamphlets, are usually written once and may be updated with a new edition. Periodicals and monographs are available in a variety of media, such as print, online, CD-ROM, or in downloadable form. Textbooks are good sources of theories in nursing. These textbooks are not primary sources but will enable you to identify appropriate theories and then locate and obtain the primary sources.

Empirical literature comprises relevant studies in journals and books, as well as unpublished studies, such as master’s theses and doctoral dissertations. A thesis is a research project completed by a master’s student as part of the requirements for a master’s degree. A dissertation is an extensive, usually original research project that is completed as the final requirement for a doctoral degree. The word empirical is defined as knowledge derived from research. You need to acquire the entire published study rather than relying on summaries or abstracts of studies. The empirical literature reviewed depends on the study problem and the type of research conducted. Research problems that have been frequently studied or are currently being investigated have more extensive empirical literature than new or unique problems. All major variables to be included in the proposed study must be included in the research literature reviewed. Other types of published information, such as descriptions of clinical situations, educational literature, and position papers, may be included in the discussion of background and significance of the research topic but because of their subjectivity often are not cited in the review of literature (Marchette, 1985; Pinch, 1995).

The published literature contains primary and secondary sources. A primary source is written by the person who originated, or is responsible for generating, the ideas published. In research publications, a primary source is written by the person or people who conducted the research. A primary theoretical source is written by the theorist who developed the theory or conceptual content. A secondary source summarizes or quotes content from primary sources. Thus, authors of secondary sources paraphrase the works of researchers and theorists. The problem with a secondary source is that the author has interpreted the works of someone else, and this interpretation is influenced by that author’s perception and bias. Sometimes errors and misinterpretations have been spread by authors using secondary sources rather than primary sources. You should use mostly primary sources to write literature reviews. Secondary sources are used only if primary sources cannot be located or if a secondary source contains creative ideas or a unique organization of information not found in a primary source. Citation is the act of quoting a source, using it as an example, or presenting it as support for a position taken.

Develop a Search Strategy

Before you begin searching the literature, you must consider exactly what information you are seeking. By writing out your search strategy, you will save considerable time in this phase of your study. A written plan helps you to (1) avoid going back along paths you have already searched, (2) retrace your steps if need be, and (3) search new paths.

Your initial search should be based on the widest possible interpretation of your topic. This strategy enables you to envision the extent of the relevant literature. As you see the results of the initial searches and begin reading the material, you will refine your topic, and then you can narrow the focus of your searches. Consider consulting with an information professional, such as a subject specialist librarian, to develop a literature search approach. These consultations can be performed via e-mail, so that communication occurs at the convenience of both the researcher and information professional. Many university libraries provide this consultation service whether or not the library user is affiliated with the university.

Select Databases to Search

A bibliographical database is a compilation of citations. The database may consist of citations relevant to a specific discipline or may be a broad collection of citations from a variety of disciplines. Databases can be divided into the following three types:

The databases first used for literature searches were in printed form. They were card catalogs, abstract reviews, and indexes. In nursing, the most relevant print database is the Cumulative Index to Nursing and Allied Health Literature (CINAHL), which contains citations of nursing literature published after 1955. Nursing scholars fondly referred to the print version of CINAHL as “the Red Books” because all the editions were bound with red covers. The print version of CINAHL is still available in libraries, and you may find it useful when searching for citations published before 1982 or if computerized databases are not available. Another print database popular among nurse researchers is the Index Medicus (IM), which was first published in 1879 and is the oldest health-related index. The Index Medicus includes some citations of nursing publications, with the number of nursing journals cited growing; however, the CINAHL contains a more extensive listing of nursing publications and uses more nursing terminology as subject headings. The earliest printed nursing index is the Nursing Studies Index, developed by Virginia Henderson, which consists of citations of nursing literature published from 1890 to 1959. The National Library of Medicine provides free access to several databases, including MEDLINE, the online equivalent of the Index Medicus, with access through Internet Grateful Med and PubMed software (available at www.nlm.nih.gov/medlineplus).

Many government agencies that produce bibliographical databases, such as the National Library of Medicine, provide free access to them. However, vendors may distribute the same data, providing “value-added” enhancements with their search software.

Full-text databases of journal articles are now available for some journals. To have access to these databases, libraries must subscribe to the service. For a variety of reasons, including the cost of receipt and storage as well as convenience to library users, many libraries are discontinuing subscriptions to paper versions of journals and, instead, subscribe to services that provide access to electronic versions. This arrangement gives the user immediate access to articles that can be read online, printed, or saved as a computer file, often whenever and wherever an affiliated user is located. As a result of these innovations, users now have more immediate access to a wide range of literature, including international sources.

Although more and more literature is available immediately in full-text form, the integration of libraries’ various bibliographical databases and full-text collections is not always seamless. Often the most useful database, in terms of ease of searching, content coverage, and terminology, may not include the text of the materials of interest. Be prepared to view the search process as one step and the literature thus identified as a second step. Even with the number of full-text digital collections, all researchers must keep in mind that not everything has been digitized, and print resources, including journals, may need to be consulted occasionally.

Select Keywords

Keywords are the major concepts or variables that must be included in your computer search. To determine keywords, identify the concepts relevant to your study. Ascertain the populations that are of particular interest in your area of study, specific interventions, measurement methods, or outcomes that are relevant. In quantitative studies, information obtained from the review of literature influences the development of several steps in the research process; these steps are listed in Table 6-1. Search strategies should be designed to ensure that you obtain adequate information for each of the steps presented in Table 6-1. In most databases, subject headings and phrases can be used, as well as single terms. Your problem and purpose statements will guide in identifying relevant terms (see Chapter 5).

You should then think of alternative terms (synonyms) that authors might use for each concept or variable you have identified. You may need to express your search using the exact words the authors have used in the literature you seek. Many bibliographical databases, such as CINAHL, have an article-specific subject analysis and provide formal subject headings for each article. Studies have shown that most searchers rarely use these formal subject terms in the searching process (Lawrence & Levy, 2004; Meats, Brassey, Heneghan, & Glasziou, 2007; Shiri & Revie, 2006). Knowledge and use of this capability can improve your searches dramatically.

These databases have a thesaurus that the researcher, as well as anyone who reads the article, can use as keyword search terms. By logging on to the database, you can access the thesaurus to select relevant terms. The formal subject terms included in the thesaurus may encompass a number of the terms that you have identified and allow you to expand your search to obtain more references or to focus your search to be more specific to your interest. This expansion or focus occurs because someone who has already read the articles has grouped all citations with similar concepts according to similar terms or concepts. For example, depending on the database, the researcher may not have to worry whether teens, teenagers, youth, adolescents, or adolescence must be searched individually, because it is likely that a search for one term will identify all. A simple way to begin identifying a database’s standardized subject terms is to display a few useful full records found by using keywords. The records are the descriptions of the articles, not the articles themselves. Examine the terminology used to describe these articles, and use the terms in additional refined searches. Frequently, word processing programs, dictionaries, and encyclopedias are helpful in identifying synonymous terms and subheadings. A combination of both keywords and formal subjects most often retrieves better search results. Some of the synonymous terms and subheadings for the research topic of postoperative experience are outlined in Table 6-2.

Truncating words can allow you to locate more citations related to that term. For example, authors might have used intervene, intervenes, intervened, intervening, intervention, or intervenor. To capture all of these terms, you can use a truncated term in your search (the form depends on the rule of the search engine being used), such as interven, interven*, or interven$. Do not truncate words to fewer than four letters; you will get far too many unwanted citations.

Pay attention to variant spellings. You may need to know, for example, that orthopedic may also be spelled orthopaedic. Consider irregular plurals, such as woman and women.

If an author is cited frequently, you can perform a search using the author’s name. In this case, you should identify the name as an author term, not a keyword term. Recognize that some databases list authors only under first and middle initials, whereas others use full first names. Identifying and using citations to seminal studies in various citation indexes or full-text databases can lead you to other, more current works that have also used the seminal studies as references. You may need to search using the full-text, free keyword, or cited references options if you are trying to locate more current references to a frequently referenced known work. Web of Knowledge, a database developed from the Science Citation Index and the Social Science Citation Index, focuses on the relationships based on these citations. Several other databases, depending on the vendor, may also have a Cited Search function. You may also know of or discover particular journals that are key to your field of research. If so, you may wish to use the journal title as a search term.

Add your selected search terms to your written search plan. As you search, add other terms that you discover from the references you locate. For each search, record (1) the name of the database you used, (2) the date you performed the search, (3) your exact search strategy, (4) the number of articles found, and (5) the percentage of relevant articles. You can develop a table to record this information from multiple search strategies, as shown in Table 6-3. Save the results of each search on your computer’s hard disk, a memory stick (flash disk), or a CD-ROM for later reference; in your written search record, document the file name of the search results.

Systematically Record References

The bibliographical information on a source should be recorded in a systematic manner, according to the format that you will use in the reference list. Many journals and academic institutions use the format developed by the American Psychological Association (APA) (2001). The reference lists in this text are presented in APA format. Computerized lists of sources usually contain complete citations for references and should be saved electronically to access complete reference citations. The editors of the APA publication manual are currently reevaluating the APA format for electronic resources. Many technological changes have occurred since the manual was published in 2001. These changes, which include some nonobvious ones like the ability of a library to link from a citation in one database to the full-text article in a totally different database and the cessation of the print Dissertation Abstracts, have created a need for a technical revision in APA formatting of electronic references. A formal supplement to the manual has been released, and a revision may be considered.

Sources that will be cited in a paper or recorded in a reference list should be cross-checked two or three times to prevent errors. Damrosch and Damrosch (1996) have identified some of the common errors that authors make when applying the APA format, and they provide guidelines for how to avoid them. The sources cited in the reference list should follow the correct format for print and online full-text versions.

Use Reference Management Software

Reference management software can make tracking the references you have obtained through your searches considerably easier. You can use such software to conduct searches and to store the information on all search fields for each reference obtained in a search, including the abstract. Once you have done so, all of the needed citation information and the abstract are readily available to you electronically when you write the literature review. As you read the articles, you can also insert comments into the reference file about each one.

Reference management software has been developed to interface directly with the most commonly used word processing software to organize the reference information using whatever citation style you stipulate. You can insert citations into your paper with just a keystroke or two. The three most commonly used software packages, along with websites that contain information about them, are as follows:

Locate Relevant Literature

Within each database, initiate your search of relevant literature by performing a separate search of each keyword you have identified. Search engines are unforgiving of misspellings, so watch your spelling carefully. Most databases allow you to indicate quickly where in the database records you wish to search for the term—in the article titles, journal names, keywords, formal subject headings, citation lists, or full texts of the articles. The most recent citations are usually listed first. You may examine the earliest citations first by changing the order of citations.

Most databases provide abstracts of the articles in which the term is cited, allowing you to get some sense of their content so you may judge whether the information is useful in relation to your selected topic. If you find the information to be an important reference, save it to a file.

At this point in the process, do not try to examine all of the citations listed. Look instead at the number of citations (or “hits”) that the search found. In some cases, you may have obtained several thousand hits—far too many to examine. For example, on October 6, 2007, a search of CINAHL using the keyword coping yielded 16,168 hits. The key term social support yielded 6155 hits (Table 6-4).

After you have performed a search, save it as a file, record the number of citations, and proceed to the next keyword. An easy way to do this is to print the search history. The search history usually has the database name noted somewhere, and the printout may have the date on it (Figure 6-1). When you have completed this activity, you will have some sense of the extent of available literature in your area of interest. At this point, you have the information you need to plan more complex searches.

Skimming Sources

Skimming a source is quickly reviewing a source to gain a broad overview of its content. You would probably read the title, the author’s name, and an abstract or introduction for the source. Then you would read the major headings and sometimes one or two sentences under each heading. Finally, you would review the conclusion or summary. Skimming enables you to make a preliminary judgment about the value of a source and to determine whether it is a primary or secondary source. Secondary sources are reviewed and used to locate cited primary sources, but they are seldom cited in a research proposal or report.

Comprehending Sources

Comprehending a source requires that you read all of it carefully. Focus on understanding major concepts and the logical flow of ideas within the source. Highlight the content you consider important; you might even want to record its ideas in the margins. Notes might be recorded on photocopies of articles, indicating where the information will be used in developing a research proposal. It is also relatively easy, with just a little practice, to copy and paste salient phrases from digital copies, as well as to record these same types of notes onto documents to accompany a photocopy or into your reference management software user notes.

The kind of information you highlight or note in the margins of a source depends on the type of study or source. The information highlighted on theoretical sources might include relevant concepts, definitions of those concepts, and relationships among them. The notes recorded in the margins of empirical literature might include relevant information about the researcher, such as (1) whether this is a critical or major researcher of a selected problem and (2) other studies this individual has conducted. For a research article, the research problem, purpose, framework, major variables, study design, sample size, data collection, analysis techniques, and findings are usually highlighted. You may wish to record quotations (including page numbers) that might be used in a review of literature section. The decision to paraphrase these quotes can be made later.

You might also record creative ideas about content that develop while you are reading a source. At this point, you will identify relevant categories for sorting and organizing sources. These categories will ultimately guide you in writing the review of literature section, and some may even be major headings in this section.

Analyzing Sources

Through analysis, you can determine the value of a source for a particular study. Analysis must take place in two stages. The first stage involves the critique of individual studies. The process of critiquing individual studies, including the steps of comprehension, comparison, analysis, evaluation, and conceptual clustering, is detailed in Chapter 26. During the critique, relevant content in sources is clearly identified, and sources are sorted into a sophisticated system of categories.

Pinch (1995) has developed a table format, which we have modified by adding two columns, that is useful in sorting information from studies into categories for analysis (Table 6-6). Conducting an analysis of sources to be used in a research proposal requires some knowledge of the subject to be critiqued, some knowledge of the research process, and the ability to exercise judgment in evaluation (Fleming & Hayter, 1974; Pinch, 1995). However, the critique of individual studies is only the first step in developing an adequate review of the literature. Any written literature review that simply critiques individual studies paragraph by paragraph is inadequate.

The second stage of analysis involves making comparisons among studies. This analysis allows you to critique the existing body of knowledge in relation to the research problem. You will be able to determine (1) theoretical formulations that have been used to explain how the variables in the problem influence one another, (2) what methodologies have been used to study the problem, (3) the methodological flaws in previous studies, (4) what is known about the problem, and (5) what the most critical gaps in the knowledge base are. The information gathered by using the table format shown in Table 6-6 can be useful in making these comparisons. Various studies addressing a research problem have approached the examination of the problem from different perspectives. They may have organized the study from different theoretical perspectives, asked different questions related to the problem, selected different variables, or used different designs. As Galvan (1999, p. 3) so wisely pointed out:

Sometimes, findings from different studies conflict, leaving understanding in that area unclear and pointing to the need for further research with improved methodologies. As Galvan (1999, p. 3) has suggested, “You may soon find yourself acting like a juror, deliberating about which researchers seem to have the most cohesive and logical arguments, which ones have the strongest evidence and so on.” O’Connor (1992) has developed a strategy for using graphing methods to visually indicate the linkage of studies. Lines are drawn from a study to all of the studies cited in it, using a time line to illustrate the development of ideas. This process is repeated until all the studies cited have been mapped.

Synthesizing Sources

Synthesis of sources involves clarifying the meaning obtained from the sources as a whole. Through synthesis, one can cluster and interrelate ideas from several sources to form a gestalt. Rather than using direct quotes from an author, you should paraphrase his or her ideas. Paraphrasing involves expressing the ideas clearly and in your own words. The meanings of these sources are then connected to the proposed study. Last, the meanings obtained from all sources are combined, or clustered, to determine the current knowledge of the research problem (Pinch, 1995). Synthesis is the basis for developing the review of literature section for a research proposal, report, or evidence-based project.

Becker (1986) has suggested that there is a drawback to reviewing the literature; it can “deform” the position you wish to take about the research topic and the direction further research should take:

Sorting Your Sources

Relevant sources (theoretical and empirical) are organized for inclusion in the different chapters of the research proposal. The sources to be included in the review of literature chapter are organized to reflect the current knowledge about the research problem. Those sources that provide background and significance for the study are included in the introduction chapter. Certain theoretical sources establish the framework for the study. Other relevant sources become the basis for defining research variables and identifying assumptions and limitations. Content from methodologically strong studies is used to direct the development of the research design, guide the selection of instruments, influence data collection and analysis, and provide a basis for interpretation of findings. Usually, at this point, a researcher is beginning to get a complete picture of his or her study and is excited about its potential. The researcher commonly feels confident about his or her knowledge of the research problem and ability to make the study a reality.

Developing the Written Review

The purpose of the written literature review is to establish a context for your study. The literature review for a study has four major sections: (1) the introduction, (2) a discussion of theoretical literature, (3) a discussion of empirical literature, and (4) a summary.

Checking References

All references used in the literature review should be carefully checked for accuracy and completeness. Anyone reviewing the literature has at some time been frustrated by inaccurate references in publications. Foreman and Kirchhoff (1987) studied the accuracy of references in 17 nursing journals; 65 of the inaccurate references were from clinical journals and 47 were from nonclinical journals. The errors were classified as major (preventing retrieval of the source) or minor (not preventing retrieval). Errors occurred more frequently in clinical journals (38.4%) than in nonclinical journals (21.3%). Clinical references also had a 4.5% incidence of major errors, whereas the nonclinical references had no major errors.

To prevent these errors, check all the citations within the text of your literature review and each citation in your reference list. Typing or keyboarding errors may result in inaccurate information. You may omit some information, planning to complete the reference later, and then forget to do so. Downloading citations from a database directly into a reference management system and using the system’s manuscript formatting functions reduces some errors but does not eliminate all of them. Use your knowledge and skills to enhance your technology use; relying on technology alone will not create a quality manuscript.

The following reference citation errors are common in research studies:

In revising your text, you may rearrange or renumber citations, resulting in inaccuracies. Biancuzzo (1997) described this sort of problem in one of her publications:

A similar problem can occur when you cite several publications written by the same author. In this case, it is easy to reference the right author but the wrong source.

To detect these easily made errors, check your references immediately before completing your paper. The most accurate check involves comparing each reference with the original journal article or online with CINAHL or other bibliographical databases.

Metasynthesis

Integrative reviews of qualitative research, or metasyntheses, are beginning to appear in the literature and will provide an important dimension to the synthesis of knowledge. Sandelowski, Docherty, and Emden (1997, p. 366) defined metasynthesis as “the theories, grand narratives, generalizations, or interpretive translations produced from the integration or comparison of findings from qualitative studies.” One difficulty is locating qualitative studies, which is more difficult than locating quantitative studies in the literature databases. Flemming and Briggs (2006) provided some strategies. Because metasynthesis is relatively new, systematic approaches to synthesizing qualitative studies is in early stages of development. A number of authors cite Noblit and Hare (1988) as the basis of their methodology for metasynthesis. Other sources cited include Estabrooks, Field, and Morse (1994); Finfgeld (2003); Jensen and Allen (1996); Kearney (2001); Kirkevold (1997); McCormick, Rodney, and Varcoe (2003); Morse, (2001); Patterson and Thorne (2003); Patterson, Thorne, Canam, and Jillings (2001); Ritzer (1992); Sandelowski (2006); Sandelowski and Barroso (2003a, 2000b); Sandelowski et al. (1997); Sandelowski, Barroso, and Voils (2007); Sherwood (1999); Thorne (1998); Thorne and Paterson (2002); Thorne, Jensen, Kearney, Noblit, and Sandelowski (2004); and Zhao (1991). Some authors are pooling strategies recommended by several sources. Others are developing their own methods. A metasynthesis is given here to demonstrate the methods used.

Coffey (2006) described her metasynthesis as follows:

Table 6-9 shows the themes extracted during the analysis. Using this table, how would you synthesize the information?

Meta-Analysis

Meta-analysis involves merging findings from many studies that have examined the same phenomenon. The design uses specific statistical analyses to determine the overall findings from a combined examination of reports of statistical findings of each study. The statistical values used include the means and standard deviations for each group in the study. One of the outcomes of a meta-analysis is the estimation of a population effect size for the topic under study. Because studies seldom have exactly the same focus, conclusions are never absolute but do give some sense of unity to knowledge within that area (O’Flynn, 1982).

One problem that researchers constantly encounter in meta-analyses is that the studies being examined are inconsistent in design quality. However, researchers conducting meta-analyses have not successfully identified a generally acceptable means to measure the research quality of studies. Brown (1991) proposed a research quality scoring method to accomplish this important task. Another problem with meta-analyses is that basic research information is often missing from research reports. Calculating effect sizes requires means and standard deviations in each study for both experimental and control groups. In addition, the beginning sample size must be reported, as well as the sample size at the time of the posttest. Often, the treatment has been poorly described, making it difficult to determine the most effective treatments (Brown, 1991).

Lee, Soeken, and Picot (2007) conducted a meta-analysis of the effectiveness of intervention in improving the mental health of informal stroke caregivers. The following describes the study:

Table 6-10 summarizes the sample studies in the Lee et al. (2007) study.

• Reviewing the existing literature related to your study is a critical step in the research process.

• The three major stages of a literature review delineated here are searching the literature, reading the literature, and writing the literature review.

• The literature consists of all written sources relevant to the topic you have selected.

• Two types of literature are predominantly used in the review of literature for research: theoretical and empirical.

• Theoretical literature includes concept analyses, models, theories, and conceptual frameworks that support a selected research problem and purpose.

• Empirical literature includes relevant studies in journals and books, as well as unpublished studies, such as master’s theses and doctoral dissertations.

• Reading and critiquing sources promotes understanding of the current knowledge of a research problem and involves skimming, comprehending, analyzing, and synthesizing content from sources.

• A thorough, organized literature review facilitates the development of a research proposal.

• The literature review for a study has four major sections: the introduction, a discussion of theoretical literature, a discussion of empirical literature, and a summary.

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