The actual term used is "kompetent", and they talk about the general competency of the individual, and assume this correlates with their suitability as politicians. They then show that their measure of competency correlates positively with municipalities having better economy and better perceived service by the citizens. They also get more votes and things like that. The measure is basically if the person makes more than average within their peer group.

Report is here: https://www.sns.se/aktuellt/sns-analys-nr-41-konskvotering-k...