The scale is the same for all, with the thick
middle horizontal representing 50% and the thinner ones below and above
indicating 40% and 60% respectively.
blue line is above the
red one, the Coalition won the seat, and vice versa. (Exception
number 1: when an Independent wins the seat. Exception number 2:
redistributions; see following points.)
Every electorate, of course, has been redistributed in the last twenty years.
Ideally for this exercise, CCDs or booth results would be retrospectively aggregated
according to current
boundaries. However, in the absence of such data I've gone for a second best
option: start with the 2001 result and for each previous election subtract the
two party preferred swing.
In the case of a redistributed seat, the swing is
from the notional two party
preferred situation before an election.
So the graphs are projections backwards from the 2001 result. That's why,
according to theirs, Parramatta and Macarthur were won by the ALP in 1998
(red above blue
line), when we know they weren't; the 1999 redistribution made them notional
One more thing: seats created since 1984 appear as if
they have been in existence for one term longer than is the case. For example, the Northern Territory seats
of Lingiari and Solomon only came into existence at the 2001 election, but to
take account of the notional swing a dummy 1998 result is shown.