The calculation method of SDI
 

(1) The calculation of indicators

The symmetrical variance is calculated as:
where
 =the value of indicator
i= dimension
j= indicator number
t= year
1
 if positive indicator
-1
 if negative indicator
The standardized factor
 
  where
N=10
The standardized variance
 

Standardized indicator:  
  if the indicator is a level or a index:
if the indicator is a ratio:
 of base year=100

The index of each dimension

where
  = weight

(2) The calculation of composite index

Composite index
w i= weight