Sėlių Square

S L I

=

∑

i = 1

n

V

i

∗ (S

i

/

V

i

− 1)

2

=

∑

i = 1

n

(S

i

−

V

i)

2

V

i

{\displaystyle \mathrm {SLI} =\sum _{i=1}^{n}{V_{i}*(S_{i}/V_{i}-1)^{2}}=\sum _{i=1}^{n}{(S_{i}-V_{i})^{2} \over V_{i}}}, where

V

i

{\displaystyle V_{i}}

is fraction of votes and

S

i

{\displaystyle S_{i}}

is fraction of seats for each of the political parties. The first part of the equation illustrates the derivation of the equation as the squared difference to the ideal seats-to-votes ratio, then weighted equally for each voter.