I have some usability testing that is taking place in several different countries. The overall budget for incentives is set (in £) but dividing this equally between all countries and then converting it to their currency would mean that some countries end up a higher-value reward because of the economy.
Any ideas on how to split this fairly for everyone?
I thought about comparing the price of staple groceries which are hopefully hold a similar value across developed countries. UK data is common knowledge for me but I couldn't find comparable data for countries in Asia and America.
Any help would be much appreciated.