A very simple analysis of PISA data.
The data contains the average (and sd) score of PISA (Program for International Student Assessment) from students by several countries thoughout the world. The last result is from 2018 and it happens since 2000.
The data is available in the folder Data, it was downloaded from the PISA results for all OECD countries
Scripts and some Fiugres are available at folder R (https://github.com/lsbastos/PISA/blob/master/R/pisa.md)