(2) Moscow pupils performed very well , at the level of the highest scoring OECD countries like Finland, Taiwan, and Korea. This is especially impressive considering the significant numbers of immigrants in that city from the North Caucasus and Central Asia, who come from poorly-scoring countries and rarely have good Russian.
(3) St.-Petersburg and Tyumen oblast [western Siberia] performed above the OECD average, while a few other regions performed at or only slightly below the OECD average.
(4) Among ethnic Russian republics, Siberian regions performed well, while the Urals and southern regions performed badly.
(5) Performance in ethnic minority republics differs dramatically. Many of the Turkic and Finno-Ugric regions, such as Tatarstan, Komi, Chuvashia, and Karelia did well; however, Mari El is a big exception. The Buddhist peoples of Asia, such as Chita oblast (now merged into Zabaykalsky Krai) and the Sakha Republic, performed relatively poorly, as did the Muslim North Caucasus region of Dagestan. Extrapolating from Dagestan, Chechnya would probably score around 400, i.e. like Brazil.
Bear these figures in mind when considering long-term investments into Russia alongside with their business climate, corruption levels, etc.
Western Russia doesn't do that well, and neither do the ex-Soviet Republics to the west of contemporary Russia. I wonder what the dysgenic effects of Leninism, Stalinism and Hitlerism were, especially on Ukraine, Belarus, Moldova, and western Russia? Many of the wealthy and middle class fled the Bolsheviks, then Stalin starved the kulaks, then murdered or imprisoned many people of above average talents, then the SS came through and shot the local leaders loyal to Stalin.
Also, here is a graph of Italian provinces with PISA scores on the horizontal axis and per capita GDP on the vertical axis.
The positive outlier above the line is Rome, the capital. The other positive outlier at the top of the chart is South Tyrol, which is a heavily German speaking area that Italy got carved out of Austria at the end of the Great War. The negative outlier is Apulia, in the southeastern heel of Italy, home to Brindisi and Lecce. I spent a day in those beat-up looking towns in 1980 and I recall a vague impression of the locals as seeming clever but anti-social, as cut-off-your-nose-to-spite-your-face types.