Maximum
Overlap Month to Month Price Indices
Let pt,m ≡ [p1t,m,p2t,m,
,pNt,m]
and qt,m ≡ [q1t,m,q2t,m,
,qNt,m]
be the month m and year t price and quantity vectors respectively. Let S(t,m)
be the set of products that is present in month m of year t and the
following month.
Define the revenue shares of product n in month m and m+1 of year t,
using the set of products that are present in month m of year t and the
subsequent month, as follows:
(a) 
;
m=1,2,
,11; nÎS(t,m);
(b) 
;
m=1,2,
,11; nÎS(t,m);
If product n is present in month m of year t and the following month,
define snt,m(t,m) using (a); if this is not the case,
define snt,m(t,m) = 0. Similarly, if product n is present
in month m of year t and the following month, define snt,m+1(t,m)
using (b); is this is not the case, define snt,m+1(t,m) =
0.
Using these share definitions, Laspeyres and Paasche formulae can be
written in revenue share and price form as follows[1]:
;
m=1,2,
,11;
;
m=1,2,
,11;