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Mixed methods synthesis

Mixed methods synthesis. — ESRC Methods Festival 2006 — James Thomas Institute of Education, University of London. Background to ‘mixed methods’ approach. Policy and practice concerns often precede, or go beyond, questions of effectiveness.

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Mixed methods synthesis

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  1. Mixed methods synthesis — ESRC Methods Festival 2006 — James ThomasInstitute of Education, University of London

  2. Background to ‘mixed methods’ approach • Policy and practice concerns often precede, or go beyond, questions of effectiveness. • Different types of questions require different combinations of study types to be included. • Different combinations of study types demand different methods of synthesis. • However, key principles of systematic reviews are not compromised.

  3. Case example of a ‘mixed methods’ synthesis What is known about the barriers to, and facilitators of, healthy eating amongst children?* *The full report of this review is available at the EPPI-Centre website: Thomas J, Sutcliffe K, Harden A, Oakley A, Oliver S, Rees R, Brunton G, Kavanagh J (2003a) Children and Healthy Eating: A systematic review of barriers and facilitators. London: EPPI-Centre, Social Science Research Unit, Institute of Education, University of London.

  4. Review process SCOPING AND MAPPING (of 272 reports of 193 studies) Review question e.g. What is known about the barriers to, and facilitators of, fruit and vegetable intake amongst children aged 4 to 10 years? ‘Views’ studies (N=8) 1. Application of inclusion criteria 2. Quality assessment 3. Data extraction 4. Thematic synthesis Trials (N=33) 1. Application of inclusion criteria 2. Quality assessment 3. Data extraction 4. Synthesis using statistical meta-analysis Trials and ‘views’ Mixed methods synthesis

  5. One review with three syntheses ‘Quantitative’ methods used to conduct a meta-analysis of data from trials. ‘Qualitative’ methods used to synthesise textual data from ‘views’ studies (aided by NVivo). Both ‘qualitative’ and ‘quantitative’ methods used to combine experimental studies of effectiveness (trials) with studies of people’s views (descriptive).

  6. SYNTHESIS 1 Quantitative (Trials) Provision of pre- and post- data on outcomes Provision of data on all outcomes measured Employment of equivalent control/comparison group Resulted in ‘high’, ‘medium’ and ‘not sound’/ ‘low’ trials SYNTHESIS 2 Qualitative (‘Views’) Quality of reporting (5 items) Sufficiency of strategies for reliability/validity (4 items) Extent to which study findings were rooted in children’s own perspectives (3 items) Quality-assessment methods

  7. Methods for synthesis 1: ‘Quantitative’ (Trials) • Effect sizes from trials pooled using: • Statistical meta-analysis • Six different outcomes • Heterogeneity across studies explored via: • Sub-group analysis • Qualitative analysis of textual data from trials

  8. Findings for synthesis 1: ‘Quantitative’ (Trials)

  9. Methods for synthesis 2: ‘Qualitative’ (Views studies) Stage 1: Thematic analysis of textual data (study authors’ descriptions of findings) = Descriptive themes Stage 2: Descriptive themes examined in light of review question = Barriers, facilitators and recommendations for interventions Stage 3:Thematic analysis revised = Analytical themes

  10. Findings of synthesis 2: Descriptive themes Food preferences Perceptions of health benefits Knowledge-behaviour gap Roles and responsibilities Non-influencing factors Chosen foods Influences on foods eaten Parental influence and food rules Breaking rules Foods in the home Provided foods Limited choice Social occasion Contradictions Foods in the school Concepts of healthy eating Healthy eating concepts Good and bad foods Health consequences

  11. Brand fruit and vegetables as ‘tasty’ rather than ‘healthy’. Reduce health emphasis of messages Do not promote fruit and vegetables in the same way within the same intervention. Create situations for children to have ownership over their food choices. Ensure messages promoting fruit and vegetables are supported by appropriate access to fruit and vegetables Findings of synthesis 2: Analytical themes, barriers, facilitators, and interventions implications 1) Children don’t see it as their role to be interested in health. 2) Children do not see future health consequences as personally relevant or credible. 3) Fruit, vegetables and confectionary have very different meanings for children. 4) Children actively seek ways to exercise their own choices with regard to foods. 5) Children value eating as a social occasion. 6) Children recognise contradiction between what is promoted and what is provided.

  12. METHODS FOR SYNTHESIS 3: ACROSS STUDY TYPES • Product of thematic synthesis of views studies was the mechanism to combine trials and views studies. • Conceptual and methodological matrix juxtaposed findings from views synthesis against findings from trial synthesis. • Comparative analysis guided by 3 questions: • Which interventions match recommendations derived from children’s views and experiences? • Which recommendations have yet to be addressed by soundly evaluated interventions? • Do those interventions which match recommendations show bigger effect sizes and/or explain heterogeneity?

  13. Synthesis 3 (Across Study Types)

  14. Synthesis 3: Sub-group Analysis Increase (standardised portions per day) in vegetable intake across trials Little or no emphasis on health messages

  15. CONCLUSIONS • Conceptually, our method allows us to integrate ‘quantitative’ estimates of benefit and harm with ‘qualitative’ understanding from people’s lives. • Technically, the insights gained from the qualitative synthesis of ‘views’ studies allows the exploration of heterogeneity in ways in which it would be difficult to imagine in advance. • Our approach has raised a number of methodological and conceptual challenges…

  16. CHALLENGES • To notions of defining sub-group analyses a priori. • To public health interventions developed and trialled solely by ‘experts’. • To traditional polarisation of qualitative and quantitative research (bridging paradigms).

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