The Promise and Problems of Meta-Analysis

Bailar, John C.

doi:10.1056/nejm199708213370810

Cited by 382 publications

(198 citation statements)

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“…A common, generic criticism of meta-analysis is that studies that are brought together differ in their characteristics and that when creating a summary of outcomes, important differences between studies may be ignored (see Bailar, 1997;Borenstein et al, 2009). However, it is important to note that one strength of meta-analysis is that the differences between studies can be addressed formally by examining the effects of moderator variables.…”

Section: Limitations Of the Current Meta-analysismentioning

confidence: 99%

Is working memory training effective? A meta-analytic review.

Melby‐Lervåg

Hulme

2013

Developmental Psychology

1,543

1,138

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It has been suggested that working memory training programs are effective both as treatments for attention-deficit/hyperactivity disorder (ADHD) and other cognitive disorders in children and as a tool to improve cognitive ability and scholastic attainment in typically developing children and adults. However, effects across studies appear to be variable, and a systematic meta-analytic review was undertaken. To be included in the review, studies had to be randomized controlled trials or quasi-experiments without randomization, have a treatment, and have either a treated group or an untreated control group. Twenty-three studies with 30 group comparisons met the criteria for inclusion. The studies included involved clinical samples and samples of typically developing children and adults. Meta-analyses indicated that the programs produced reliable short-term improvements in working memory skills. For verbal working memory, these near-transfer effects were not sustained at follow-up, whereas for visuospatial working memory, limited evidence suggested that such effects might be maintained. More importantly, there was no convincing evidence of the generalization of working memory training to other skills (nonverbal and verbal ability, inhibitory processes in attention, word decoding, and arithmetic). The authors conclude that memory training programs appear to produce short-term, specific training effects that do not generalize. Possible limitations of the review (including age differences in the samples and the variety of different clinical conditions included) are noted. However, current findings cast doubt on both the clinical relevance of working memory training programs and their utility as methods of enhancing cognitive functioning in typically developing children and healthy adults.

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Section: Limitations Of the Current Meta-analysismentioning

confidence: 99%

Is working memory training effective? A meta-analytic review.

Melby‐Lervåg

Hulme

2013

Developmental Psychology

1,543

1,138

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“…Although there were no instances of a trial and metaanalysis giving opposing answers, meta-analysis failed to predict a subsequent trial's finding that a treatment was effective or ineffective in one-third of the 40 outcomes. Bailar [63] commented that LeLorier's study also casts doubt on the validity of large trials: is the 'truth' represented by the trial or the meta-analysis? He writes, 'I know of no instance in medicine in which a meta-analysis led to a major change in policy before the time when a careful, conventional review of the literature led to the same change.…”

Section: Interpreting Meta-analysesmentioning

confidence: 99%

Anaesthesia and evidence‐based medicine

Goodman

1998

Anaesthesia

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“…Consequently, the integration of the produced evidence into clinical practice can be very challenging for the clinician [17]. As with other study designs, the risks and advantages of MAs are still a matter of discussion in the medical research community [14,[18][19][20][21][22][23][24]. The weaknesses of MAs include among others the fact that occasionally the results of a research area are oversimplified, [25] there are errors in classifying of the studies or errors in estimating effect sizes, there is only a small number of well conducted studies to be included in the analysis, the primary studies present low quality or small sample sizes, and the primary data included in the analysis present significant heterogeneity [26].…”

Section: Introductionmentioning

confidence: 99%

Meta-Analyses and Orthodontic Evidence-Based Clinical Practice in the 21st Century~!2009-09-21~!2009-10-05~!2010-07-16~!

Papadopoulos¹

2010

TODENTJ

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Abstract:Introduction: Aim of this systematic review was to assess the orthodontic related issues which currently provide the best evidence as documented by meta-analyses, by critically evaluating and discussing the methodology used in these studies. Material and Methods:Several electronic databases were searched and handsearching was also performed in order to identify the corresponding meta-analyses investigating orthodontic related subjects. In total, 197 studies were retrieved initially. After applying specific inclusion and exclusion criteria, 27 articles were identified as meta-analyses treating orthodontic-related subjects.Results: Many of these 27 papers presented sufficient quality and followed appropriate meta-analytic approaches to quantitatively synthesize data and presented adequately supported evidence. However, the methodology used in some of them presented weaknesses, limitations or deficiencies. Consequently, the topics in orthodontics which currently provide the best evidence, include some issues related to Class II or Class III treatment, treatment of transverse problems, external apical root resorption, dental anomalies, such as congenital missing teeth and tooth transposition, frequency of severe occlusal problems, nickel hypersensitivity, obstructive sleep apnea syndrome, and computer-assisted learning in orthodontic education. Conclusions:Only a few orthodontic related issues have been so far investigated by means of MAs. In addition, for some of these issues investigated in the corresponding MAs no definite conclusions could be drawn, due to significant methodological deficiencies of these studies. According to this investigation, it can be concluded that at the begin of the 21 st century there is evidence for only a few orthodontic related issues as documented by meta-analyses, and more well-conducted high quality research studies are needed to produce strong evidence in order to support evidence-based clinical practice in orthodontics.

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The Promise and Problems of Meta-Analysis

Cited by 382 publications

References 10 publications

Is working memory training effective? A meta-analytic review.

Is working memory training effective? A meta-analytic review.

Anaesthesia and evidence‐based medicine

Meta-Analyses and Orthodontic Evidence-Based Clinical Practice in the 21st Century~!2009-09-21~!2009-10-05~!2010-07-16~!

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