Based on the source link I belive the article writer misunderstood that part. These studies tend to be about the mandatory screening (mustering) process. Back t

Based on the source link I belive the article writer misunderstood that part. These studies tend to be about the mandatory screening (mustering) process. Back then it was mandatory for all males to go through two days of testing (physiology/medical/intelligence/psychology). Out of these some number where selected for military service. This is a data goldmine for studies these days since the data can be directly linked to various outcomes later in life on an individual level via their national identification numbers. tl;dr: Most likely it includes both those that did military service at first and those that went directly to college. (Source: Am Swedish, did this screening/mustering in 1996.)