By Helen Gao, Sinosphere blog @ nytimes.com, Jan. 23, 2014

Is the education system in Shanghai, China’s largest and most internationalized city, really a paradigm of academic excellence and educational equity, or does its stellar performance mask a grimmer reality, in which one of the world’s largest barriers to education opportunities plagues tens of thousands of its residents?

The question has been the subject of intense debate among scholars and educators since December, when the Program for International Student Assessment, or PISA, released the results of its 2012 tests [....]

While many Western observers have rushed to uncover the secret to Shanghai’s success, others argue that PISA has portrayed Shanghai in an overly positive light by failing to present the whole picture.

In a series of articles published on the Brookings Institution’s website, Tom Loveless, a former professor at Harvard’s Kennedy School of Government and an expert on education policy, questioned the inclusiveness and representativeness of PISA’s Shanghai samples. He pointed out a glaring oddity in the PISA data: Shanghai, a city of 24 million, reports only slightly more than 100,000 15-year-olds, a number similar to that reported in Portugal and Greece, countries with less than half Shanghai’s population.

“Where did all of Shanghai’s 15-year-olds go?” Mr. Loveless asked.  His answer is that China’s restrictions on internal migration are to blame [....]