WRT Finnish special ed in general (from your link):
'A well-organized and effective special education system, run by university-trained teachers has shifted towards full inclusion; equality means strong dedication to the idea of "no child left behind‟, found especially in primary and special education (Simola 2005)'.
Special education specifically:
'Only 2% of Finnish pupils are in special teaching institutes; those who are undergoing ordinary education in comprehensive school have carefully-tailored support that corresponds to pupils‟ needs; The relatively small scattering of Finnish PISA results can be understood through the support given to the lower-achieving pupils. The fact that the Finnish average performance in the lowest percentile groups is without any reservations the best in the world is evidence to back this claim. (Hautamäki et al. 2008)
Teacher training -
'Good training for all Finnish teachers in diagnosing students with learning difficulties and in adapting their instruction to the varying learning needs and styles of their students'.
'Teachers in Finland place a premium on two strategies that might seem at odds with each other, but are mutually reinforcing: Students are expected to take responsibility for their own education by giving classes their full attention. Yet, at the same time, a great deal of help is provided to those
who struggle. (Des Moines Register 2010)
? Strong emphasis on early depiction of learning difficulties, with appropriate intervention through remedial help or special education (Kupiainen 2010)'.
Regarding exclusion of student scores from the PISA calculations:
' Rules allowed countries to exclude up to 5% of the target population.
Exclusions for intellectual disability depended on the professional opinion of the school principal or by other qualified staff -
- a completely uncontrollable source of uncertainty. It appears that
some countries defined additional criteria: Denmark, Finland, Ireland, Poland, and Spain excluded students with dyslexia; Denmark also students with dyscalculia; Luxembourg recently immigrated students.
- Actual student exclusion rates of OECD countries varied from 0.7% to 7.3%. Canada, Denmark, New Zealand, Spain, and the USA exceeded the 5% limit. Nevertheless, data from these countries were fully included in all analyses'
===> I don't think you can confidently conclude that Finland excluded more than 5%. Finland may not have excluded its allowed 5% and then an additional unknown percentage on top of that.
Variance between top and lowest achievers in Finland tends to be much smaller than elsewhere so there may not be any advantage to be gained by Finland excluding its full whack. charts pps. 30, 31, 32 and text p. 33
A strange complaint --
'In PISA 2000, the English and French versions of 60 stimulus texts were compared: the French texts contained on average 12% more words and 19% more letters. Mathematics items of PISA 2003 had 16% more characters in German than in English.'
Maybe it takes more words to express a thought in French? Maybe French words tend to be longer than English words? Again with the German-English 'more characters in German than in English' problem: could it be that German has longer words? Just pondering here -- it seems to me that longer words (for instance German compound nouns) would only be an issue if it can be assumed students can't read them accurately or quickly and I really don't know if this would be the case for native speakers.