I'm working with a social psychologist on a research study of the determinants of anti-immigrant attitudes among adolescents in 28 countries. Our data come from the 1999 IEA study of 90,000 14-year-old students in Australia, Belgium, Bulgaria, Chile, Colombia, Cyprus, Czech Republic, Denmark, England, Estonia, Finland, Germany, Greece, Hong
Kong, Hungary, Italy, Latvia, Lithuania, Norway, Poland, Portugal, Romania, Russia, Slovak Republic, Slovenia, Sweden, Switzerland, and the United States. The data set includes some reasonable measures of attitudes, but we want to add an independent variable that assesses government policies or 'openness' to immigration. This is, of course, a very challenging quest because the meaning of even simple measures varies greatly from country to country, and because there are few measures for which even somewhat comparable data are available for most of the countries in our study. Three such measures that we are considering are:

1) whether the country has signed the Convention Relating to the Status of Refugees, 2) refugees per capita, and 3) per capita country contributions to UNHCR. Even these have problems of comparability. I'm struggling with whether there are straight forward measures related to other immigration policies that are worth including. Simple comparisons of percentages of immigrants across countries are problematic, since nations vary greatly in what they include in the numerator (e.g. Papademetriou's example of the millions of ethnic Russians who were classified as internal migrants until the break-up of the Soviet Union in the 1990s, and then re-classified as international migrants; he also points out that some countries, such as the US, count unauthorized migrants and individuals with short-term visas among the 'foreign-born', while many other countries do not.)

I would like to hear from people who have advice regarding the selection of other measures that meet the criteria
of reasonable validity, comparability and availability to measure government policies toward immigrants. I'm also interested in suggestions of papers and names of researchers whom I might contact to educate myself about the implications and caveats of various alternative measures. This one question has truly opened a Pandora's box!