Combining findings Combining findings from different from different
research research
The EBM workshopThe EBM workshop
A.A.Haghdoost, MD; PhD of A.A.Haghdoost, MD; PhD of EpidemiologyEpidemiology
[email protected]@kmu.ac.ir
Qualitative versus quantitative approachQualitative versus quantitative approach
EBM workshop Combining evidences A.A.Haghdoost
Ratio
nal
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.
EBM workshop Combining evidences A.A.Haghdoost
Ratio
nal
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.
EBM workshop Combining evidences A.A.Haghdoost
Quantita
tive a
pp
roach
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
EBM workshop Combining evidences A.A.Haghdoost
Qualita
tive a
pp
roach
If studies measured different parameters, such as measurement of depression using different questioners
If someone would like to combine the findings of qualitative studies
EBM workshop Combining evidences A.A.Haghdoost
PureReplications
ConceptualReplications
Meta analysis Meta synthesis
EBM workshop Combining evidences A.A.Haghdoost
Gu
idelin
e
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
EBM workshop Combining evidences A.A.Haghdoost
Meta
synth
esis
• “Putting together” findings from qualitative studies
• A relatively vague and little known comparative method of synthesizing qualitative studies – for the “accumulation of knowledge”
EBM workshop Combining evidences A.A.Haghdoost
Meth
od
olo
gy o
f meta
-synth
esis
(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
EBM workshop Combining evidences A.A.Haghdoost
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
Meth
od
olo
gy o
f meta
-synth
esis
(2)
EBM workshop Combining evidences A.A.Haghdoost
Arg
um
en
ts in Fa
vor o
f Meta
-S
ynth
esis
• 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
EBM workshop Combining evidences A.A.Haghdoost
Arg
um
en
ts Ag
ain
st Qu
alita
tive
Meta
-synth
esis
• You can’t 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
Top Related