The statistical index

where is the price per unit in period and is the quantity produced in the initial period.

Kenney, J. F. and Keeping, E. S. Mathematics of Statistics, Pt. 1, 3rd ed. Princeton, NJ: Van Nostrand, pp. 65-67, 1962.

CITE THIS AS:

Weisstein, Eric W. "Laspeyres' Index." From MathWorld--A Wolfram Web Resource. http://mathworld.wolfram.com/LaspeyresIndex.html