A Cross-Temporal Meta-Analysis of Raven's Progressive Matrices: Age groups and developing versus developed countries

• The Flynn effect was investigated in 734 samples and 202,468 total participants from 48 countries, covering a period of 64 years.
• A relationship was found between RPM mean scores and year of publication (the Flynn effect), moderated by sample age grouping and country type.
• Participants in developed countries had higher scores, but IQ gain over time was much larger in developing countries.

While many studies have investigated the rise in IQ over time in various countries, the present study attempts to fill the gap in the Flynn effect literature by considering data with various sample sizes, and different study designs, age groups and types of country. A Cross-Temporal Meta-Analysis (CTMA) technique was used to examine the relationship between mean IQ scores from the Raven's Progressive Matrices (RPM) and years of publication, moderated by age group and types of country over a period of 64 years (1950–2014). In all, 202,468 participants were included from 48 countries. We conclude that there is an obvious link between mean IQ scores and years of publication. Importantly, interaction analyses indicate that both age group and types of country moderate this relationship.