Good catch... I wasn't reading thoroughly enough...
I went back and looked at the data in the study to see whether it used the preliminary research or only for successfully recruited candidates and discovered this:
"Cohorts born before 1962 were subject to a different scoring norm,
and cohorts born later than 1991 faced a radically different conscription
process with less than 50% invited for in-person testing after completing a
web-administered survey. As a result, representative data are not available
for later birth cohorts. Data for immigrants are excluded as information on
full family size and exact birth order is of lesser quality, while selection into
scoring is markedly different as immigrants typically do not face mandatory
conscription testing but need to self-select into conscription."
So it seems the preliminary examination does not include enough information or the conscription in general has changed to radically for that information to be reliable.
I went back and looked at the data in the study to see whether it used the preliminary research or only for successfully recruited candidates and discovered this:
"Cohorts born before 1962 were subject to a different scoring norm, and cohorts born later than 1991 faced a radically different conscription process with less than 50% invited for in-person testing after completing a web-administered survey. As a result, representative data are not available for later birth cohorts. Data for immigrants are excluded as information on full family size and exact birth order is of lesser quality, while selection into scoring is markedly different as immigrants typically do not face mandatory conscription testing but need to self-select into conscription."
So it seems the preliminary examination does not include enough information or the conscription in general has changed to radically for that information to be reliable.