How is synthesis related to the research process

The range of different methods for synthesising qualitative research has been growing over recent years [ 1 , 2 ], alongside an increasing interest in qualitative synthesis to inform health-related policy and practice [ 3 ].

While the terms 'meta-analysis' a statistical method to combine the results of primary studies , or sometimes 'narrative synthesis', are frequently used to describe how quantitative research is synthesised, far more terms are used to describe the synthesis of qualitative research.

This profusion of terms can mask some of the basic similarities in approach that the different methods share, and also lead to some confusion regarding which method is most appropriate in a given situation. This paper does not argue that the various nomenclatures are unnecessary, but rather seeks to draw together and review the full range of methods of synthesis available to assist future reviewers in selecting a method that is fit for their purpose.

It also represents an attempt to guide the reader through some of the varied terminology to spring up around qualitative synthesis. Other helpful reviews of synthesis methods have been undertaken in recent years with slightly different foci to this paper.

Two recent studies have focused on describing and critiquing methods for the integration of qualitative research with quantitative [ 4 , 5 ] rather than exclusively examining the detail and rationale of methods for the synthesis of qualitative research.

Two other significant pieces of work give practical advice for conducting the synthesis of qualitative research, but do not discuss the full range of methods available [ 6 , 7 ]. We begin our Discussion by outlining each method of synthesis in turn, before comparing and contrasting characteristics of these different methods across a range of dimensions. Readers who are more familiar with the synthesis methods described here may prefer to turn straight to the 'dimensions of difference' analysis in the second part of the Discussion.

In their seminal work of , Noblit and Hare proposed meta-ethnography as an alternative to meta-analysis [ 8 ]. They cited Strike and Posner's [ 9 ] definition of synthesis as an activity in which separate parts are brought together to form a 'whole'; this construction of the whole is essentially characterised by some degree of innovation, so that the result is greater than the sum of its parts.

They also borrowed from Turner's theory of social explanation [ 10 ], a key tenet of which was building 'comparative understanding' [[ 8 ], p22] rather than aggregating data. To Noblit and Hare, synthesis provided an answer to the question of 'how to "put together" written interpretive accounts' [[ 8 ], p7], where mere integration would not be appropriate. Noblit and Hare's early work synthesised research from the field of education.

Three different methods of synthesis are used in meta-ethnography. One involves the 'translation' of concepts from individual studies into one another, thereby evolving overarching concepts or metaphors. Noblit and Hare called this process reciprocal translational analysis RTA. Refutational synthesis involves exploring and explaining contradictions between individual studies. Lines-of-argument LOA synthesis involves building up a picture of the whole i.

The authors conceptualised this latter approach as a type of grounded theorising. Britten et al [ 11 ] and Campbell et al [ 12 ] have both conducted evaluations of meta-ethnography and claim to have succeeded, by using this method, in producing theories with greater explanatory power than could be achieved in a narrative literature review.

While both these evaluations used small numbers of studies, more recently Pound et al [ 13 ] conducted both an RTA and an LOA synthesis using a much larger number of studies 37 on resisting medicines. These studies demonstrate that meta-ethnography has evolved since Noblit and Hare first introduced it. Campbell et al claim to have applied the method successfully to non-ethnographical studies.

Based on their reading of Schutz [ 14 ], Britten et al have developed both second and third order constructs in their synthesis Noblit and Hare briefly allude to the possibility of a 'second level of synthesis' [[ 8 ], p28] but do not demonstrate or further develop the idea. The former would involve looking to see whether the same concept, theory etc exists in different studies; the latter would involve the construction of a bigger picture or theory i.

LOA synthesis. They also talk about comparing or integrating imported concepts e. Kearney [ 16 ], Eaves [ 17 ] and Finfgeld [ 18 ] have all adapted grounded theory to formulate a method of synthesis. Key methods and assumptions of grounded theory, as originally formulated and subsequently refined by Glaser and Strauss [ 19 ] and Strauss and Corbin [ 20 , 21 ], include: simultaneous phases of data collection and analysis; an inductive approach to analysis, allowing the theory to emerge from the data; the use of the constant comparison method; the use of theoretical sampling to reach theoretical saturation; and the generation of new theory.

Eaves cited grounded theorists Charmaz [ 22 ] and Chesler [ 23 ], as well as Strauss and Corbin [ 20 ], as informing her approach to synthesis. Glaser and Strauss [ 19 ] foresaw a time when a substantive body of grounded research should be pushed towards a higher, more abstract level.

As a piece of methodological work, Eaves undertook her own synthesis of the synthesis methods used by these authors to produce her own clear and explicit guide to synthesis in grounded formal theory. Kearney stated that 'grounded formal theory', as she termed this method of synthesis, 'is suited to study of phenomena involving processes of contextualized understanding and action' [[ 24 ], p] and, as such, is particularly applicable to nurses' research interests.

As Kearney suggested, the examples examined here were largely dominated by research in nursing. Eaves synthesised studies on care-giving in rural African-American families for elderly stroke survivors; Finfgeld on courage among individuals with long-term health problems; Kearney on women's experiences of domestic violence. Kearney explicitly chose 'grounded formal theory' because it matches 'like' with 'like': that is, it applies the same methods that have been used to generate the original grounded theories included in the synthesis — produced by constant comparison and theoretical sampling — to generate a higher-level grounded theory.

The wish to match 'like' with 'like' is also implicit in Eaves' paper. This distinguishes grounded formal theory from more recent applications of meta-ethnography, which have sought to include qualitative research using diverse methodological approaches [ 12 ].

Thomas and Harden [ 25 ] have developed an approach to synthesis which they term 'thematic synthesis'. This combines and adapts approaches from both meta-ethnography and grounded theory.

The method was developed out of a need to conduct reviews that addressed questions relating to intervention need, appropriateness and acceptability — as well as those relating to effectiveness — without compromising on key principles developed in systematic reviews. They applied thematic synthesis in a review of the barriers to, and facilitators of, healthy eating amongst children.

Free codes of findings are organised into 'descriptive' themes, which are then further interpreted to yield 'analytical' themes. This approach shares characteristics with later adaptations of meta-ethnography, in that the analytical themes are comparable to 'third order interpretations' and that the development of descriptive and analytical themes using coding invoke reciprocal 'translation'.

It also shares much with grounded theory, in that the approach is inductive and themes are developed using a 'constant comparison' method. A novel aspect of their approach is the use of computer software to code the results of included studies line-by-line, thus borrowing another technique from methods usually used to analyse primary research. Textual narrative synthesis is an approach which arranges studies into more homogenous groups.

Lucas et al [ 26 ] comment that it has proved useful in synthesising evidence of different types qualitative, quantitative, economic etc. Typically, study characteristics, context, quality and findings are reported on according to a standard format and similarities and differences are compared across studies.

Structured summaries may also be developed, elaborating on and putting into context the extracted data [ 27 ]. Lucas et al [ 26 ] compared thematic synthesis with textual narrative synthesis. They found that 'thematic synthesis holds most potential for hypothesis generation' whereas textual narrative synthesis is more likely to make transparent heterogeneity between studies as does meta-ethnography, with refutational synthesis and issues of quality appraisal.

This is possibly because textual narrative synthesis makes clearer the context and characteristics of each study, while the thematic approach organises data according to themes. However, Lucas et al found that textual narrative synthesis is 'less good at identifying commonality' p2 ; the authors do not make explicit why this should be, although it may be that organising according to themes, as the thematic approach does, is comparatively more successful in revealing commonality. Paterson et al [ 28 ] have evolved a multi-faceted approach to synthesis, which they call 'meta-study'.

The sociologist Zhao [ 29 ], drawing on Ritzer's work [ 30 ], outlined three components of analysis, which they proposed should be undertaken prior to synthesis. These are meta-data-analysis the analysis of findings , meta-method the analysis of methods and meta-theory the analysis of theory.

Collectively, these three elements of analysis, culminating in synthesis, make up the practice of 'meta-study'. Paterson et al pointed out that the different components of analysis may be conducted concurrently.

Paterson et al argued that primary research is a construction; secondary research is therefore a construction of a construction. There is need for an approach that recognises this, and that also recognises research to be a product of its social, historical and ideological context.

Such an approach would be useful in accounting for differences in research findings. For Paterson et al, there is no such thing as 'absolute truth'. Meta-study was developed to study the experiences of adults living with a chronic illness. Meta-data-analysis was conceived of by Paterson et al in similar terms to Noblit and Hare's meta-ethnography see above , in that it is essentially interpretive and seeks to reveal similarities and discrepancies among accounts of a particular phenomenon.

Meta-method involves the examination of the methodologies of the individual studies under review. Part of the process of meta-method is to consider different aspects of methodology such as sampling, data collection, research design etc, similar to procedures others have called 'critical appraisal' CASP [ 31 ].

However, Paterson et al take their critique to a deeper level by establishing the underlying assumptions of the methodologies used and the relationship between research outcomes and methods used. Meta-theory involves scrutiny of the philosophical and theoretical assumptions of the included research papers; this includes looking at the wider context in which new theory is generated. Paterson et al described meta-synthesis as a process which creates a new interpretation which accounts for the results of all three elements of analysis.

The process of synthesis is iterative and reflexive and the authors were unwilling to oversimplify the process by 'codifying' procedures for bringing all three components of analysis together.

Greenhalgh et al [ 32 ]'s meta-narrative approach to synthesis arose out of the need to synthesise evidence to inform complex policy-making questions and was assisted by the formation of a multi-disciplinary team.

Their approach to review was informed by Thomas Kuhn's The Structure of Scientific Revolutions [ 33 ], in which he proposed that knowledge is produced within particular paradigms which have their own assumptions about theory, about what is a legitimate object of study, about what are legitimate research questions and about what constitutes a finding. Paradigms also tend to develop through time according to a particular set of stages, central to which is the stage of 'normal science', in which the particular standards of the paradigm are largely unchallenged and seen to be self-evident.

As Greenhalgh et al pointed out, Kuhn saw paradigms as largely incommensurable: 'that is, an empirical discovery made using one set of concepts, theories, methods and instruments cannot be satisfactorily explained through a different paradigmatic lens' [[ 32 ], p].

Greenhalgh et al synthesised research from a wide range of disciplines; their research question related to the diffusion of innovations in health service delivery and organisation. They thus identified a need to synthesise findings from research which contains many different theories arising from many different disciplines and study designs.

Based on Kuhn's work, Greenhalgh et al proposed that, across different paradigms, there were multiple — and potentially mutually contradictory — ways of understanding the concept at the heart of their review, namely the diffusion of innovation. Bearing this in mind, the reviewers deliberately chose to select key papers from a number of different research 'paradigms' or 'traditions', both within and beyond healthcare, guided by their multidisciplinary research team.

They took as their unit of analysis the 'unfolding "storyline" of a research tradition over time' [[ 32 ], p and sought to understand diffusion of innovation as it was conceptualised in each of these traditions. The results of this exercise led to maps of 13 'meta-narratives' in total, from which seven key dimensions, or themes, were identified and distilled for the synthesis phase of the review.

Dixon-Woods et al [ 34 ] developed their own approach to synthesising multi-disciplinary and multi-method evidence, termed 'critical interpretive synthesis', while researching access to healthcare by vulnerable groups. Critical interpretive synthesis is an adaptation of meta-ethnography, as well as borrowing techniques from grounded theory.

The authors stated that they needed to adapt traditional meta-ethnographic methods for synthesis, since these had never been applied to quantitative as well as qualitative data, nor had they been applied to a substantial body of data in this case, papers.

Dixon-Woods et al presented critical interpretive synthesis as an approach to the whole process of review, rather than to just the synthesis component. It involves an iterative approach to refining the research question and searching and selecting from the literature using theoretical sampling and defining and applying codes and categories. It also has a particular approach to appraising quality, using relevance — i.

The authors also stress, as a defining characteristic, critical interpretive synthesis's critical approach to the literature in terms of deconstructing research traditions or theoretical assumptions as a means of contextualising findings. Dixon-Woods et al rejected reciprocal translational analysis RTA as this produced 'only a summary in terms that have already been used in the literature' [[ 34 ], p5], which was seen as less helpful when dealing with a large and diverse body of literature.

Instead, Dixon-Woods et al adopted a lines-of-argument LOA synthesis, in which — rejecting the difference between first, second and third order constructs — they instead developed 'synthetic constructs' which were then linked with constructs arising directly from the literature. The influence of grounded theory can be seen in particular in critical interpretive synthesis's inductive approach to formulating the review question and to developing categories and concepts, rejecting a 'stage' approach to systematic reviewing, and in selecting papers using theoretical sampling.

Dixon-Woods et al also claim that critical interpretive synthesis is distinct in its 'explicit orientation towards theory generation' [[ 34 ], p9]. Jim Banning is the author of 'ecological triangulation' or 'ecological sentence synthesis', applying this method to the evidence for what works for youth with disabilities. He borrows from Webb et al [ 36 ] and Denzin [ 37 ] the concept of triangulation, in which phenomena are studied from a variety of vantage points. His rationale is that building an 'evidence base' of effectiveness requires the synthesis of cumulative, multi-faceted evidence in order to find out 'what intervention works for what kind of outcomes for what kind of persons under what kind of conditions' [[ 38 ], p1].

Ecological triangulation unpicks the mutually interdependent relationships between behaviour, persons and environments. The method requires that, for data extraction and synthesis, 'ecological sentences' are formulated following the pattern: 'With this intervention, these outcomes occur with these population foci and within these grades ages , with these genders Brunton et al [ 40 ] and Oliver et al [ 41 ] have applied a 'framework synthesis' approach in their reviews.

Framework synthesis is based on framework analysis, which was outlined by Pope, Ziebland and Mays [ 42 ], and draws upon the work of Ritchie and Spencer [ 43 ] and Miles and Huberman [ 44 ]. Its rationale is that qualitative research produces large amounts of textual data in the form of transcripts, observational fieldnotes etc.

The sheer wealth of information poses a challenge for rigorous analysis. Framework synthesis offers a highly structured approach to organising and analysing data e. Brunton et al applied the approach to a review of children's, young people's and parents' views of walking and cycling; Oliver et al to an analysis of public involvement in health services research. Framework synthesis is distinct from the other methods outlined here in that it utilises an a priori 'framework' — informed by background material and team discussions — to extract and synthesise findings.

As such, it is largely a deductive approach although, in addition to topics identified by the framework, new topics may be developed and incorporated as they emerge from the data. The synthetic product can be expressed in the form of a chart for each key dimension identified, which may be used to map the nature and range of the concept under study and find associations between themes and exceptions to these [ 40 ].

There are three other approaches to synthesis which have not yet been widely used. One is an approach using content analysis [ 45 , 46 ] in which text is condensed into fewer content-related categories.

Another is 'meta-interpretation' [ 47 ], featuring the following: an ideographic rather than pre-determined approach to the development of exclusion criteria; a focus on meaning in context; interpretations as raw data for synthesis although this feature doesn't distinguish it from other synthesis methods ; an iterative approach to the theoretical sampling of studies for synthesis; and a transparent audit trail demonstrating the trustworthiness of the synthesis.

In addition to the synthesis methods discussed above, Sandelowski and Barroso propose a method they call 'qualitative metasummary' [ 15 ]. It is mentioned here as a new and original approach to handling a collection of qualitative studies but is qualitatively different to the other methods described here since it is aggregative; that is, findings are accumulated and summarised rather than 'transformed'.

Metasummary is a way of producing a 'map' of the contents of qualitative studies and — according to Sandelowski and Barroso — 'reflect [s] a quantitative logic' [[ 15 ], p].

The frequency of each finding is determined and the higher the frequency of a particular finding, the greater its validity. The authors even discuss the calculation of 'effect sizes' for qualitative findings.

Qualitative metasummaries can be undertaken as an end in themselves or may serve as a basis for a further synthesis. Having outlined the range of methods identified, we now turn to an examination of how they compare with one another. It is clear that they have come from many different contexts and have different approaches to understanding knowledge, but what do these differences mean in practice?

Our framework for this analysis is shown in Additional file 1 : dimensions of difference [ 48 ]. We have examined the epistemology of each of the methods and found that, to some extent, this explains the need for different methods and their various approaches to synthesis.

The first dimension that we will consider is that of the researchers' epistemological assumptions. Spencer et al [ 49 ] outline a range of epistemological positions, which might be organised into a spectrum as follows:.

Subjective idealism : there is no shared reality independent of multiple alternative human constructions. Scientific realism : it is possible for knowledge to approximate closely an external reality. Thus, at one end of the spectrum we have a highly constructivist view of knowledge and, at the other, an unproblematized 'direct window onto the world' view.

Nearly all of positions along this spectrum are represented in the range of methodological approaches to synthesis covered in this paper. The originators of meta-narrative synthesis, critical interpretive synthesis and meta-study all articulate what might be termed a 'subjective idealist' approach to knowledge.

Paterson et al [ 28 ] state that meta-study shies away from creating 'grand theories' within the health or social sciences and assume that no single objective reality will be found. Primary studies, they argue, are themselves constructions; meta-synthesis, then, 'deals with constructions of constructions' p7. Greenhalgh et al [ 32 ] also view knowledge as a product of its disciplinary paradigm and use this to explain conflicting findings: again, the authors neither seek, nor expect to find, one final, non-contestable answer to their research question.

Critical interpretive synthesis is similar in seeking to place literature within its context, to question its assumptions and to produce a theoretical model of a phenomenon which — because highly interpretive — may not be reproducible by different research teams at alternative points in time [[ 34 ], p11]. Methods used to synthesise grounded theory studies in order to produce a higher level of grounded theory [ 24 ] appear to be informed by 'objective idealism', as does meta-ethnography.

Kearney argues for the near-universal applicability of a 'ready-to-wear' theory across contexts and populations. This approach is clearly distinct from one which recognises multiple realities.

The emphasis is on examining commonalities amongst, rather than discrepancies between, accounts. This emphasis is similarly apparent in most meta-ethnographies, which are conducted either according to Noblit and Hare's 'reciprocal translational analysis' technique or to their 'lines-of-argument' technique and which seek to provide a 'whole' which has a greater explanatory power.

Although Noblit and Hare also propose 'refutational synthesis', in which contradictory findings might be explored, there are few examples of this having been undertaken in practice, and the aim of the method appears to be to explain and explore differences due to context, rather than multiple realities. Despite an assumption of a reality which is perhaps less contestable than those of meta-narrative synthesis, critical interpretive synthesis and meta-study, both grounded formal theory and meta-ethnography place a great deal of emphasis on the interpretive nature of their methods.

This still supposes a degree of constructivism. Although less explicit about how their methods are informed, it seems that both thematic synthesis and framework synthesis — while also involving some interpretation of data — share an even less problematized view of reality and a greater assumption that their synthetic products are reproducible and correspond to a shared reality.

This is also implicit in the fact that such products are designed directly to inform policy and practice, a characteristic shared by ecological triangulation. Notably, ecological triangulation, according to Banning, can be either realist or idealist. Banning argues that the interpretation of triangulation can either be one in which multiple viewpoints converge on a point to produce confirming evidence i.

Thus, although ecological triangulation views reality as complex, the approach assumes that it can be approximately knowable at least when the realist view of ecological triangulation is adopted and that interventions can and should be modelled according to the products of its syntheses.

While pigeonholing different methods into specific epistemological positions is a problematic process, we do suggest that the contrasting epistemologies of different researchers is one way of explaining why we have — and need — different methods for synthesis. Variation in terms of the extent of iteration during the review process is another key dimension.

All synthesis methods include some iteration but the degree varies. Meta-ethnography, grounded theory and thematic synthesis all include iteration at the synthesis stage; both framework synthesis and critical interpretive synthesis involve iterative literature searching — in the case of critical interpretive synthesis, it is not clear whether iteration occurs during the rest of the review process. Meta-narrative also involves iteration at every stage. Banning does not mention iteration in outlining ecological triangulation and neither do Lucas or Thomas and Harden for thematic narrative synthesis.

It seems that the more idealist the approach, the greater the extent of iteration. Another dimension along which we can look at different synthesis methods is that of quality assessment. When the approaches to the assessment of the quality of studies retrieved for review are examined, there is again a wide methodological variation. It might be expected that the further towards the 'realism' end of the epistemological spectrum a method of synthesis falls, the greater the emphasis on quality assessment.

In fact, this is only partially the case. Framework synthesis, thematic narrative synthesis and thematic synthesis — methods which might be classified as sharing a 'critical realist' approach — all have highly specified approaches to quality assessment. The review in which framework synthesis was developed applied ten quality criteria: two on quality and reporting of sampling methods, four to the quality of the description of the sample in the study, two to the reliability and validity of the tools used to collect data and one on whether studies used appropriate methods for helping people to express their views.

Studies which did not meet a certain number of quality criteria were excluded from contributing to findings. Similarly, in the example review for thematic synthesis, 12 criteria were applied: five related to reporting aims, context, rationale, methods and findings; four relating to reliability and validity; and three relating to the appropriateness of methods for ensuring that findings were rooted in participants' own perspectives. Studies which were deemed to have significant flaws were excluded and sensitivity analyses were used to assess the possible impact of study quality on the review's findings.

Thomas and Harden's use of thematic narrative synthesis similarly applied quality criteria and developed criteria additional to those they found in the literature on quality assessment, relating to the extent to which people's views and perspectives had been privileged by researchers.

It is worth noting not only that these methods apply quality criteria but that they are explicit about what they are: assessing quality is a key component in the review process for both of these methods. Again, Banning writes of excluding studies deemed to be of poor quality. Greenhalgh et al's meta-narrative review [ 32 ] modified a range of existing quality assessment tools to evaluate studies according to validity and robustness of methods; sample size and power; and validity of conclusions.

The authors imply, but are not explicit, that this process formed the basis for the exclusion of some studies. Although not quite so clear about quality assessment methods as framework and thematic synthesis, it might be argued that meta-narrative synthesis shows a greater commitment to the concept that research can and should be assessed for quality than either meta-ethnography or grounded formal theory. The originators of meta-ethnography, Noblit and Hare [ 8 ], originally discussed quality in terms of quality of metaphor, while more recent use of this method has used amended versions of CASP the Critical Appraisal Skills Programme tool, [ 31 ] , yet has only referred to studies being excluded on the basis of lack of relevance or because they weren't 'qualitative' studies [ 8 ].

In grounded theory, quality assessment is only discussed in terms of a 'personal note' being made on the context, quality and usefulness of each study. Finally, meta-study and critical interpretive synthesis — two more subjective idealist approaches — look to the content and utility of findings rather than methodology in order to establish quality. While earlier forms of meta-study included only studies which demonstrated 'epistemological soundness', in its most recent form [ 51 ] this method has sought to include all relevant studies, excluding only those deemed not to be 'qualitative' research.

Critical interpretive synthesis also conforms to what we might expect of its approach to quality assessment: quality of research is judged as the extent to which it informs theory. The threshold of inclusion is informed by expertise and instinct rather than being articulated a priori. In terms of quality assessment, it might be important to consider the academic context in which these various methods of synthesis developed.

The reason why thematic synthesis, framework synthesis and ecological triangulation have such highly specified approaches to quality assessment may be that each of these was developed for a particular task, i. The concept of quality assessment in relation to RCTs is much less contested and there is general agreement on criteria against which quality should be judged. Critical interpretive synthesis, the meta-narrative approach and the meta-theory element of meta-study all share some common ground in that their review and synthesis processes include examining all aspects of the context in which knowledge is produced.

In conducting a review on access to healthcare by vulnerable groups, critical interpretive synthesis sought to question 'the ways in which the literature had constructed the problematics of access, the nature of the assumptions on which it drew, and what has influenced its choice of proposed solutions' [[ 34 ], p6]. Although not claiming to have been directly influenced by Greenhalgh et al's meta-narrative approach, Dixon-Woods et al do cite it as sharing similar characteristics in the sense that it critiques the literature it reviews.

Meta-study uses meta-theory to describe and deconstruct the theories that shape a body of research and to assess its quality. One aspect of this process is to examine the historical evolution of each theory and to put it in its socio-political context, which invites direct comparison with meta-narrative synthesis.

Studies of undergraduate students reveal conflicting conclusions regarding relationships between advanced scholarly study and citation efficacy. Although Franz found that no participants enjoyed learning citation style, Goldstein determined in a larger study that all participants watched felt comfortable citing sources, suggesting that variables among participant and control group populations must be examined more closely.

Although Perez expanded on Franz's original study with a larger, more diverse sample Before you can start writing, you need to organize your notes in a way that allows you to see the relationships between sources. One way to begin synthesizing the literature is to put your notes into a table. A summary table collates the key points of each source under consistent headings.

Each row in the table lists one source, and each column identifies a specific part of the source. For example, you might include columns for things like aims, methods, variables, population, sample size, and conclusion. For each study, you briefly summarize each of these aspects. You can also include columns for your own evaluation and analysis. The summary table gives you a quick overview of the key points of each source.

This allows you to group sources by relevant similarities, as well as noticing important differences or contradictions in their findings. Each column in the table lists one source.

Each row is labelled with a specific concept, topic or theme that recurs across all or most of the sources. The purposes of the table is to identify the common points that connect the sources, as well as identifying points where they diverge or disagree. For shorter papers, your outline can just identify the focus of each paragraph; for longer papers, you might want to divide it into sections with headings.

If your sources cover a broad time period, and you found patterns in how researchers approached the topic over time, you can organize your discussion chronologically. If the literature covers various different topics, you can organize it thematically. That means that each paragraph or section focuses on a specific theme and explains how that theme is approached in the literature.

That means grouping together studies based on the type of research they did and discussing the findings that emerged from each method. If your topic involves a debate between different schools of thought, you can organize it theoretically. That means comparing the different theories that have been developed and grouping together papers based on the position or perspective they take on the topic, as well as evaluating which arguments are most convincing. What sets a synthesis apart from a summary is that it combines various sources.

The easiest way to think about this is that each paragraph should discuss a few different sources, and you should be able to condense the overall point of the paragraph into one sentence. This is called a topic sentence , and it usually appears at the start of the paragraph. The topic sentence signals what the whole paragraph is about; every sentence in the paragraph should be clearly related to it. For an effective synthesis, you can use topic sentences to link back to the previous paragraph, highlighting a point of debate or critique:.

By using topic sentences, you can ensure that your paragraphs are coherent and clearly show the connections between the articles you are discussing. As you write your paragraphs, avoid quoting directly from sources: use your own words to explain the commonalities and differences that you found in the literature.