pri čemer pomeni - o ceno za dani osnovni agregat v obdobju t, pa pomeni vzorec cen v osnovnem agregatu v obdobju t. Ta vzorec se lahko v praksi sprotno mesečno dopolnjuje ali bolj običajno, kadar cen ni mogoče pridobiti, na daljše obdobje. Kadar med osnovnim obdobjem b in t ni dopolnitev, postane, enostavno razmerje aritmetičnih sredin (ali podobno z geometrijsko formulo, ki je opisana zgoraj).
where Pi denotes the i price quotation for a given elementary aggregate in the period t and s denotes the sample of prices obtained for the elementary aggregate in period t. This sample may in practice be updated monthly or, more usually, when prices cannot be obtained, over longer periods. If between base period b and period t there is no replenishing at all I becomes I = FORMULA,the simple ratio of arithmetic means (or similarly with the geometric formula described above).