re: "how we can get reliable information and knowledge?"
This is where the world is an unfair world. With a kid in school, both me and my wife do a lot of research. A kid without education-focused parent would probably be at a disadvantage.
I learned what are the "reliable" sources. Many "reliable sources" will have their own biases but I learned to mentally filter the noise out while get to the music. Much good information can be obtained by combining sources, but then of course I am collecting info and making decisions with the full load of my own biases.
re: "TIMMS and PISA: The result of the test does not in any way affect the future of the pupil being tested"
It may not affect individuals directly but it will affect the nation or region which will end up affecting the individual indirectly. A company selecting a facility location will not select a place where an educated work force is hard to get.
Its OK that you or me or any other induviduals can find "reliable sources". But - what about when your politicians cherry-pick results as they find them suitable to
their agenda? Is that OK? The mix of education and politics is more like advanced mud wrestling than science, so don't expect them to have your best in mind.
The problem with the fact that the test does not affect the pupils directly
is a real problem because the test result will be more or less flawed. Do you think a 12 year old boy tired of school bother much about the nations best 10 years ahead? I have a lot of experience with 16 - 19 year old boys tired of school, and I can tell you they don't give shit about it.
These tests are considered important by most governments, and they use them to change the educational system. Sometimes they panic, and make changes every three year when a new test is published.
The real problem is not that the US or UK or Norway or any country is not on the top. The real problem is that almost all developed nations are performing equally poor (or good if you are an optimist). And as I said; I do really believe the gap between east and west is smaller than we can read from the results.
The big question for me is how this can happen when we have a lot of different school systems and lot of different cultures but still almost the same performance. What kind of changes to a given school system will prove much better than any other in this environment?