Week 05 Flashcards
Meta means…
beyond
What does a meta-analysis do….?
summarises results, improves precision of estimates of effects in population
Do all systematic reviews have meta-analyses?
No
______ review is the traditional literature review where author selects, reads and summarises without systematic process
narrative
A narrative review has risk of ___
bias (unreliability)
Which is more reliable, narrative or systematic review?
systematic
What are some disadvantages of systematic reviews/meta analysis ?
- Cant review information that isn’t there
- Can’t improve on poor quality information
- May be difficult to validly combine statistical results from studies with different methods
- Many systematic reviews give open finding (inconclusive) because sufficient high quality studies are lacking
A ____________ is a statistical method of combining results from multiple studies
meta-analysis
“pooled effect size” is a _____ result combining samples from multiple studies
single
Do larger or smaller samples provide more precise estimates?
Larger (more information)
List reporting biases affecting whether research findings are published at all (4)?
- Publication bias: unfashionable research topics may miss out on publication
- Time lag bias: rapid or delayed publication of results
- Duplicate publication bias: the same research findings published in more than one article; also known as “salami slicing”
- Outcome reporting bias: marked preference for studies with “significant” results; non-significant may be just as important
List biases affecting whether report included in review (4)?
- Citation bias: whether the report appears in a reference list affects its chance of being spotted
- Database inclusion bias: article not in database is harder to find
- Language bias:
preferences for studies in english - Personal biases of researchers doing the review
Funnel plot shows effect size by ____ size
sample
Bias against trials with small samples and negative/positive effects?
negative
If no publication bias, funnel plot will look symmetrical or asymmetrical?
symmetrical
Heterogeneity = ??
difference or diversity
Can clinical heterogeneity can cause statistical heterogeneity ?
Yes
Appraising systematic reviews: Validity of the methods used in the review
- Clearly focussed question with clear eligibility criteria
- High quality, relevant studies
- Assessment of bias in the studies
- Results combined across studies, but only if reasonable to do so
Appraising systematic reviews: Results of the review
- Overall results of the review are presented
- Results are sufficiently precise
Appraising systematic reviews: Relevance of the results to your clinical practice
- Outcome considered from the practitioners perspective
- Applicability of results to your own target population
What is ecological fallacy?
“what applies to the group, will also apply to the individual”
- not sound concept
- Internal validity threat
Value of systematic reviews to practitioners depend on (2)?
- Availability and quality of primary studies for review
- Methods used to conduct the review
Meta-analysis estimates overall statistical effect size
- Effectively increases the sample size, leading to higher precision
- Feasibility affected by heterogeneity among studies
- Can identify bias in individual studies
Standard review process applies to quantitative research
- Strong emphasis on clinical trials but observation studies eligible
- Qualitative research developing alternatives - meta synthesis
Systematic reviews can/can’t be affected by same biases as primary studies and biases specific to systematic reviews (cannot improve on original evidence quality –> heterogeneity is a risk)
can