Combining findings from different research

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Combining findings from different research
Qualitative versus quantitative approach

• The EBM workshop

A.A.Haghdoost, MD PhD of Epidemiology Ahaghdoost
_at_kmu.ac.ir
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Rational

• Researchers used to think the aim of a single
  study was to decide if a given effect was "real"
  (statistically significant).
• But they put little faith in a single study of an
  effect, no matter how good the study and how
  statistically significant.

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Rational

• Each study produces a different estimate of the
  magnitude.
• When many studies were done, someone would write
  a narrative ( qualitative) review trying to
  explain why the effect was/wasn't real in the
  studies.
• Or would carry out a study to estimate the
  magnitude of an effect with adequate precision
  using others findings.

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Quantitative approach

• Meta-analysis combines the effects from all
  studies to give an overall mean effect and other
  important statistics.
• The measured effects should be comparable and
  estimate a common quantity

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Qualitative approach

• If studies measured different parameters, such as
  measurement of depression using different
  questioners
• If someone would like to combine the findings of
  qualitative studies

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Guideline

• Clinical practice guidelines are recommendations
  for clinicians and consumers about optimal and
  appropriate care for specific clinical situations
• Nowadays, formal guideline are generated by using
  both qualitative and quantitative methods

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Meta synthesis

• Putting together findings from qualitative
  studies
• A relatively vague and little known comparative
  method of synthesizing qualitative studies for
  the accumulation of knowledge

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Methodology of meta-synthesis (1)

• Systematic review?!
• Focus on search strategies, quality and
  aggregation
• A critical assessment and evaluation of research
  (not simply a summary) that attempts to address a
  focused clinical question using methods designed
  to reduce the likelihood of bias.
• Guyatt and Rennie 2002

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Methodology of meta-synthesis (2)

• Since the papers are usually extremely
  heterogeneous, you can group the articles into
  categories of similar domains.
• For each article, central themes should be
  extracted and common metaphors identified for the
  whole category.
• Content analysis and compare the similarity and
  differences between study findings

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Arguments in Favor of Meta-Synthesis

• Qualitative research may be endangered and
  marginalized by its failure to sum up or put
  together and not be little islands of
  knowledge
• Need to compare findings and data in the same
  topical area
• Need to extend beyond modernism to post modernism

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Arguments Against Qualitative Meta-synthesis

• You cant sum up poems or songs!
• Variations of method and underlying theoretical
  assumptions
• Diversity of practices
• Destroys the integrity of individual studies
• Thins our deep descriptions
• De-contextualizes material