The statistical index
where 
 is the price per unit in period 
, 
 is the quantity produced in period 
, and 
 the value of the 
 units.
 
	    
	
    
The statistical index
where 
 is the price per unit in period 
, 
 is the quantity produced in period 
, and 
 the value of the 
 units.
Weisstein, Eric W. "Geometric Mean Index." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/GeometricMeanIndex.html