The datasets had missing data (i.e., some year’s values were missing from the UN data).
In cases where the missing data was at the beginning or end, data was extrapolated from nearby data.
In other cases, data was filled in with interpolated data.
For the purposes of the study, it was not important that the data be entirely accurate.
Participants were told to answer questions based on what they saw, not on any preconceived notions or beliefs about countries.