March 2021protocol via Twitter in order to crowd-source additional relevant studies not identified through the search. All titles and abstracts identified in our search were double-screened using the Rayyan online application. Fourth, to ensure that our analysis is comprehensive in terms of recent and relevant research, on February 14, 2022, and on August 8, 2022, we conducted two comprehensive forward and backward citation searches of all eligible studies identified in the above steps. As noted above, in order to be included in our research sample, estimates of learning progress had to be based on test score measures that could be standardized across studies using Cohen's d.From the studies that meet our inclusion criteria we extracted all estimates of learning progress of school-aged children during the COVID-19 pandemic, separately for math and reading and for different school grades. We also extract the corresponding sample size, standard error, date(s) of measurement, author name(s), and country. Last, we recorded whether studies differentiate between children's socio-economic background, which measure is used to this end, and whether studies find an increase, decrease or no change in learning inequality. We contacted study authors, if any of the information was missing in the study. Data extraction was performed by the first author and validated independently by the second author, with discrepancies resolved through discussion and by conferring with the third author. All extracted information was manually compiled in a spreadsheet using Microsoft Excel (v.16.66.1) and then imported into the statistical program Stata (v.17.0) for our analyses.
TimingOur data collection started on April 27, 2021 and ended on August 8, 2022.
Data exclusionsStudies were included in the systematic review and meta-analysis based on the inclusion criteria described in the pre-registered study protocol (https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021249944). The PRISMA flow diagram in the manuscript (Figure 1) shows the number of studies included and excluded in the systematic review and meta-analysis, as well as the reasons for exclusion.
Non-participationNo participants were involved in this study.
RandomizationRandomization is not applicable to this study, since our systematic review and meta-analysis examines all available estimates of learning progress of school-aged children during the COVID-19 pandemic.
Reporting for specific materials, systems and methodsWe require information from authors about some types of materials, experimental systems and methods used in many studies. Here, indicate whether each material, system or method listed is relevant to your study. If you are not sure if a list item applies to your research, read the appropriate section before selecting a response.