This section focuses on the formal synthesis of qualitative research. General debate about the appropriateness of combining qualitative studies continues, and more specifically whether different types of qualitative research, based on different theoretical assumptions and methods should be combined. Sometimes authors’ claims about the theoretical underpinnings of their work are not always closely related to the methods actually used. A recent investigation suggested it is very difficult to draw firm boundaries around what is, and is not, a particular type of qualitative research as many authors failed to give any definition.52 Despite these problems this same investigation also found that it is possible to synthesise across different traditions52 and indeed some review teams consider the combining of data from multiple theoretical and methodological traditions a strength of the review.24
A number of different methods have been proposed for the synthesis of qualitative findings, many based on approaches used in primary research.2, 3, 12
Some of the methods maintain the qualitative form of the evidence such as meta-ethnography and some involve converting qualitative findings into a quantitative form such as content analysis. It has been argued that perhaps the least useful way of dealing with qualitative data is to turn them into quantitative data.53 Box 6.2 outlines some of the methods proposed. This is not a comprehensive list. Choice of method will be influenced by a number of factors including the question posed, likely number of relevant studies and undoubtedly the knowledge and expertise of the team undertaking the review.
Many of the methods are still at a developmental stage and there are relatively few examples of their application. An overview of syntheses of qualitative research published between 1988 and 2004 identified 42 such syntheses of which meta-ethnography was the method most commonly used.46 Consequently there is as yet little evaluation of the relative strengths and weaknesses of available methods and few guidelines exist for judging quality. However, the recent development of a comprehensive framework for good practice offers potential, both for researchers wanting to carry out a synthesis and for those wishing to use the findings of a synthesis.52
It is important to note that there are many different terms used to describe the various methods, some of which have been applied inconsistently. Some terms such as ‘qualitative meta-analysis’, ‘meta-study’ and ‘meta-synthesis’ appear to have been used in an over-arching way to describe any synthesis of qualitative research. The use of the term meta-synthesis to describe any synthesis of qualitative research has been criticised on the grounds that it is not specific to qualitative research, and is frequently technically incorrect, since what is being attempted is not at the meta-level of the synthesis but at the meta-level of the included studies (Mary Dixon-Woods, personal communication).
| Box 6.2: Methods proposed for the synthesis of qualitative evidence | |
|
Synthesis method |
Description |
|
Meta-ethnography51
|
A set of techniques for synthesising qualitative studies. It involves the selection, comparison and analysis of studies to create new interpretations or concepts. Key stages include the reading and re-reading of studies; determining how the studies are related by listing key concepts and comparing and contrasting them; translating the studies into one another and synthesising the translations to identify concepts which go beyond individual accounts and can be used to produce a new interpretation.
It has been used to address questions about the meanings of medicines,54, 55 the barriers and facilitators of adherence to TB treatment,56, 19 lay experiences of diabetes and diabetes care,36 children’s perspectives of growing up in disadvantage57 and teenage mothers’ experiences of their lives.58 |
|
Thematic analysis/synthesis43 |
The identification of important or recurrent themes. Findings are summarised under thematic headings. Information is tabulated allowing identification of prominent themes and offering structured ways of dealing with the data in each theme. More recently the method has been refined, such that a new method - thematic synthesis - has emerged.43, 59
It has been used to address questions about barriers to and facilitators of healthy eating amongst children;60 young people, pregnancy and social exclusion44 and accidental injury, risk taking behaviour and the social circumstances in which young people live.61 |
|
Grounded theory (constant comparative method)62 |
Grounded theory was originally developed for use with primary studies and describes methods for sampling, data collection and analysis. Its potential application to the synthesis of multiple qualitative studies has recently been reported.2, 63 One particular element – the constant comparative method – has received most attention as it offers a set of procedures for analysing qualitative evidence.64
It has been used to address questions about women’s experiences of domestic violence,65 living with HIV infection66 and caring in nursing.24 |
|
Qualitative research synthesis: Qualitative meta-synthesis3 |
A set of techniques for the interpretive integration of qualitative research findings. |
|
Content analysis67 |
A systematic technique for categorising data into themes and counting frequency of themes. |
|
Case survey68 |
Formal process for coding data from qualitative cases into a quantitative form. |
|
Qualitative comparative analysis69 |
A method for summarising and comparing data from case studies using Boolean logic |
|
Qualitative research synthesis: Qualitative meta-summary3 |
A set of techniques for the quantitative aggregation of qualitative research findings. |
|
Narrative synthesis70 |
A general framework and specific tools and techniques that help to increase transparency and trustworthiness. Can be applied to reviews of quantitative or qualitative research as individual tools and techniques can be selected according to the type of study design and data included in the review.
The framework has been applied to questions relating to implementation of domestic smoke alarms.70 |