Such a tool may also be useful for meta-analysts and systematic reviewers to ensure that their studies are well designed, conducted, and reported. One way to do this is by assessing their quality by means of a standardized tool. Therefore, it is important that users of SRs/MAs results (e.g., clinicians, researchers, and policy makers) consider the methodological quality of these studies. Conclusions may be affected by deficiencies in designing, performing, and reporting these SRs/MAs. Yet, poorly conducted SRs/MAs can lead to inaccurate inferences about the intervention effectiveness.
Comprehensive meta analysis single subject serial#
Another feature that has to be considered is the possible presence of serial dependency or autocorrelation in which the sequential measurements are more similar compared to farther measurements, violating the assumption of independence 17,18.Ĭonducting a SCED SR or MA could provide better insights into the overall effectiveness of interventions, as well as about factors that moderate the effect. Such a time trend should be accounted for in calculating effect sizes 4,16. For instance, the outcome variable could systematically decrease or increase over time even without being exposed to any intervention. SCED data have specific features that should be taken into account while calculating effect sizes in individual studies and synthesizing the effect sizes in a meta-analysis afterwards otherwise, biased estimates might be obtained and statistical inferences may be flawed. A SR can include a meta-analysis (MA), which refers to a statistical integration of the findings from individual studies, typically by combining and comparing observed effect sizes 15. In order to decrease the possible systematic bias to answer particular research question(s), specific methods could be applied in SR 14. A SR is a kind of literature review to identify, evaluate, and aggregate all relevant studies on the same topic. To overcome this issue of generalizability, SCEDs can be replicated across participants, and systematic review (SR) approaches can be applied to synthesize the results 4,12,13. SCEDs are frequently used in a variety of different fields such as psychology and educational sciences to evaluate the effectiveness of interventions of interest 7–11.ĭue to the small number of participants, the main issue of SCEDs is limited generalizability of their findings. Within each specific case, the measurements are compared across conditions or phases to investigate whether introducing the intervention has a causal effect on one or more outcomes 2,4–7. In this kind of designs, outcomes of interest are measured repeatedly for one or multiple cases under at least two conditions (i.e., typically a control phase followed by an intervention phase). Single-case experimental designs (SCEDs) are alternative research designs that do not require many participants (or cases) and therefore are well suited to be used for studying rare phenomena, e.g., specific diseases or disabilities 1–3. In order to get reliable effect size estimates and reach an acceptable level of statistical power, a large sample size of study participants is required in these designs. In this kind of designs, the participants are randomly assigned to either intervention or control groups and the means of one or more dependent variables are compared to assess the effectiveness of the intervention. In order to investigate a certain intervention effect, the classic research design is a group comparison experimental design. These tools and guidelines can help meta-analysts, reviewers, and users to organize and evaluate the quality and reliability of the findings. In the current study, some existing tools for assessing the quality of SRs/MAs that might also be helpful for SCED MAs will be reviewed briefly. One way to improve the reliability and validity of SCED MAs and therefore to provide more confidence in MA/SR findings to practitioners and clinicians to decide on a particular intervention is the use of high-quality standards when conducting and reporting MAs/SRs. As MA/SR’s conclusions are used as an evidence base for making decisions in practice and policy, the methodological quality and reporting standards of SRs/MAs are of uttermost importance. Single-case experimental design (SCED) studies are becoming more prevalent in a variety of different fields and are increasingly included in meta-analyses (MAs) and systematic reviews (SRs). Natasha Beretvas 4, and Wim Van den Noortgate 1ġFaculty of Psychology and Educational Sciences & imec-Itec, KU Leuven (University of Leuven), BelgiumĢUniversity of South Florida, Tampa, Florida, USAģUniversity at Albany – State University of New York, New York, USAĤUniversity of Texas at Austin, Texas, USA Improving the Methodological Quality of Single-Case Experimental Design Meta-Analysis Laleh Jamshidi 1*, Lies Declercq 1, John M.
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