Survey for measuring literacy rate

It seems as though many countries use surveys to measure literacy. However, this survey method is subjective. For example, when given this question, "Can you read and write, with understanding, a simple sentence relating to your daily life? Yes/No" some people may simply believe that being able to read and write their name is being "literate". Since measuring literacy can be so subjective, it must be difficult to get an accurate view of international literacy. Every country measures this in a different manner. Therefore, any list that ranks countries by literacy rate must be skewed to some extent.