When an international report shows New Zealand's maths, science and reading scores for 15-year-olds are in "absolute freefall" - to quote Labour's education spokesman, Chris Hipkins - two questions emerge. One is, can we trust the test results? The second question is: if we can, what should we do about it?
New Zealand fell this week from 7th to 13th in reading, from 7th to 18th in science and from 13th to 22nd in maths in the OECD's Programme for International Study Assessment (Pisa) report for 2012. The drop can be only partly explained by the inclusion in the last decade of new city states - Shanghai-China, Hong Kong-China and Macau-China - which have test-based education systems and tend to dominate the top of the rankings.
Some critics have pointed out the international country rankings are highly suspect, as the test results combine real data with computer-generated "plausible results".
Danish statistician Sven Kreiner told the Listener this week that this unreliability could swing Japan's reading ranking anywhere between 8th and 40th and Britain's from 14th to 30th. However, most experts agree that a country's results, over time, tell a more reliable story and New Zealand is also slipping here.
Our scores have declined in all three subjects and the biggest drop has occurred in the past three years. Maths has consistently fallen from a mark of 537 and a ranking of 4th in 2000 to 500 last year, barely above the OECD average. The trend is consistent with other recent national and international results. In the 2011 Trends in Mathematics and Science Study (TIMSS) published a year ago, New Zealand 9-year-olds finished bottom-equal among developed nations. Half were unable to add 218 and 191.