Population is related to Measurement. Measurement is related to Distance. Distance is related to Trip. 
Whip is a type of Flexibility. Whip is related to Control. Regulator is a type of Control. 
Population <--RelatedTo--> Measurement <--RelatedTo--> Distance <--RelatedTo--> Trip 
Flexibility <--IsA-- Whip <--RelatedTo--> Control <--IsA-- Regulator 