14
code the main competitor of the focal candidate using previous electoral returns and the
general patterns of national party competition.
14
I examine the LDP and DPJ results in
this context, to better understand the linkage between expenditures and vote shares in the
new system. I begin this endeavor with the LDP.
I evaluate Hypothesis 1 and 2 using the percentage of the SMD vote share
received by LDP and DPJ candidates as the main dependent variable. The vote shares of
LDP candidates have a range from 10% to 55%, with a mean average of 29%. In contrast,
the vote shares of DPJ candidates have a range of 3% to 41%, with a mean average of
23%. To model the vote share, the main explanatory variables will be the different types
of own and rival expenditures in addition to a variety of controls for candidate and
district characteristics:
VOTE =
β
0
+
β
1
KOENKAI
+
β
2
COMPETITION +
β
3
INCUMBENT +
β
4
PREVIOUS TERMS +
β
5
NUMBER +
β
6
DID +
β
7
OWN CPS +
β
8
RIVAL CPS
+
β
9
OWN FUND +
β
10
OWN PARTY+
β
11
OWN KOENKAI +
β
12
RIVAL
FUND +
β
13
RIVAL PARTY +
β
14
RIVAL KOENKAI
+
ε
,
where
β
0
through
β
14
are ordinary least squares estimates and
ε
is an error term.
•
VOTE, the dependent variable, is the candidate’s percentage of the district vote share in
the 2000 Lower House election.
•
KOENKAI is a variable for the total number of support groups registered for the focal
candidate in 2000. I expect
β
1
to be positive.
•
COMPETITION is a variable for the difference in the district vote share between the
focal candidate and the next finisher in the 2000 Lower House election.
•
INCUMBENT is a dummy variable that is coded “1” if the candidate has previously won
election to the Lower House. I expect
β
3
to be positive.
•
PREVIOUS TERMS is a variable for the total number of previous terms a candidate has
been elected to the Lower House prior to the 2000 election.
14
In most districts, the main competitor is the previous incumbent. When there is not an incumbent, I
match the main parties against each other. In the case of the LDP, for example, I pit candidates against the
main competition of either a previous incumbent in the district or with the candidate from the main rival
party.
Convention