The Corps of INSEE (Corps de l'INSEE) is a technical grand corps de l'Etat. Its members are public servant known as Administrateurs de l'INSEE. Most of them work for INSEE or in the French Ministry of the Economy.
People entering the Corps are educated at the ENSAE. Most of them are from the École polytechnique and are known as X-INSEE. The rest come from the École Normale Supérieure, the regular curriculum of the ENSAE, ENSAI or internal promotion.
References
Corps de l'INSEE Wikipedia(Text) CC BY-SA