Are the survey response rates similar across the countries you wish to include in your analysis or are there any issues around bias due to differential survey response rates? It is becoming increasingly difficult to gain co-operation from the public for surveys in many developed countries and response rates have fallen in many countries over the past 15 years.
Although high response rates help minimise the potential bias they do not protect against it completely. It is possible to have a high response rate and still have bias if all those who did not respond are similar to each other and different from those who did participate.
