Chapter 5 Election data in R

Elections tend to create fascinating data sets. They are spatial in nature, comparable over time (i.e. the number of electorates roughly stays the same) - and more importantly they are consequential for all Australians.

Australia’s compulsory voting system is a remarkable feature of our Federation. Every three-ish years we all turn out at over 7,000 polling booths our local schools, churches, and community centres to cast a ballot and pick up an obligatory election dat sausage. The byproduct is a fascinating longitudinal and spatial data set.

The following code explores different R packages, election data sets, and statistical processes aimed at exploring and modelling federal elections in Australia.

One word of warning: I use the term electorates, divisions, and seats interchangeably throughout this chapter.

5.1 Getting started

Let’s load up some packages

#Load packages
library(ggparliament)
library(eechidna)
library(dplyr)
library(ggplot2)
library(readxl)
library(tidyr)
library(tidyverse)
library(purrr)
library(knitr)
library(broom)
library(absmapsdata)
library(rmarkdown)
library(bookdown)

Some phenonmenal Australia economists and statisticians have put together a handy election package called eechidna. It includes three main data sets for the most recent Australia federal election (2019).

  • fp19: first preference votes for candidates at each electorate

  • tpp19: two party preferred votes for candidates at each electorate

  • tcp19: two candidate preferred votes for candidates at each electorate

They’ve also gone to the trouble of aggregating some census data to the electorate level. This can be found with the abs2016 function.

data(fp19)
data(tpp19)
data(tcp19)
data(abs2016)

# Show the first few rows
#head(tpp16) %>% kable("simple")
#head(tcp16) %>% kable("simple")
DT::datatable(tpp19)
DT::datatable(tcp19)

5.2 Working with election maps

As noted in the introduction, elections are spatialin nature.

Not only does geography largely determine policy decisions, we see that many electorates vote for the same party (or even the same candidate) for decades. How electorate boundaries are drawn is a long story (see here, here, and here).

The summary version is the AEC carves up the population by state and territory, uses a wack formula to decide how many seats each state should be allocated, then draws maps to try and get a roughly equal number of people in each electorate. Oh… and did I mention for reasons that aren’t worth explaining that Tasmania has to have at least 5 seats? Our Federation is a funny thing. Anyhow, at time of writing this is how the breakdown of seats looks.

State/Territory Number of members of the House of Representatives
New South Wales 47
Victoria 39
Queensland 30
Western Australia 15
South Australia 10
Tasmania 5
Australian Capital Territory 3
Northern Territory 2*
TOTAL 151

Note: The NT doesn’t have the population to justify it’s second seat - and the AEC scheduled to dissolve it, but Parliament intervened in late 2020 and a bill was passed to make both seats were kept (creating 151 nationally).

CED_map <- ced2018 %>%
           ggplot()+
           geom_sf()+
           labs(title="Electoral divisions in Australia",
               subtitle = "It turns out we divide the country in very non-standard blocks",
               caption = "Data: Australian Bureau of Statistics 2016",
               x="",
               y="",
               fill="Median age") + 
           theme_minimal() +
            theme(axis.ticks.x = element_blank(),axis.text.x = element_blank())+
            theme(axis.ticks.y = element_blank(),axis.text.y = element_blank())+
            theme(panel.grid.major = element_blank(), panel.grid.minor = element_blank())+
            theme(legend.position = "right")+
            theme(plot.title=element_text(face="bold",size=12))+
            theme(plot.subtitle=element_text(size=11))+
            theme(plot.caption=element_text(size=8))


CED_map_remove_6 <- ced2018 %>%
                    dplyr::filter(!ced_code_2018 %in% c(506,701,404,511,321,317)) %>%   
                    ggplot()+
           geom_sf()+
           labs(title="194 electoral divisions in Australia",
               subtitle = "Turns out removing the largest 6 electorates makes a difference",
               caption = "Data: Australian Bureau of Statistics 2016",
               x="",
               y="",
               fill="Median age") + 
           theme_minimal() +
            theme(axis.ticks.x = element_blank(),axis.text.x = element_blank())+
            theme(axis.ticks.y = element_blank(),axis.text.y = element_blank())+
            theme(panel.grid.major = element_blank(), panel.grid.minor = element_blank())+
            theme(legend.position = "right")+
            theme(plot.title=element_text(face="bold",size=12))+
            theme(plot.subtitle=element_text(size=11))+
            theme(plot.caption=element_text(size=8))

CED_map
CED_map_remove_6

5.3 Answering some simple questions

Let’s start by answering a simple question: who won the election? For this we’ll need to use the two-candidate preferred data set (to make sure we capture all the minor parties that won seats).

who_won <- tcp19 %>% 
  filter(Elected == "Y") %>% 
  group_by(PartyNm) %>% 
  tally() %>% 
  arrange(desc(n)) 

# inspect
who_won %>% kable("simple")
PartyNm n
LIBERAL PARTY 133
AUSTRALIAN LABOR PARTY 131
NATIONAL PARTY 19
INDEPENDENT 5
CENTRE ALLIANCE 2
KATTER’S AUSTRALIAN PARTY (KAP) 2
THE GREENS (VIC) 2

Next up let’s see which candidates won with the smallest percentage of votes

who_won_least_votes_prop <- fp16 %>% 
  filter(Elected == "Y") %>% 
  arrange(Percent) %>% 
  mutate(candidate_full_name = paste0(GivenNm, " ", Surname, " (", CandidateID, ")")) %>% 
  dplyr::select(candidate_full_name, PartyNm, DivisionNm, Percent)

who_won_least_votes_prop %>% head %>% kable("simple")
candidate_full_name PartyNm DivisionNm Percent
MICHAEL DANBY (28267) AUSTRALIAN LABOR PARTY MELBOURNE PORTS 27.00
CATHY O’TOOLE (28997) AUSTRALIAN LABOR PARTY HERBERT 30.45
JUSTINE ELLIOT (28987) AUSTRALIAN LABOR PARTY RICHMOND 31.05
TERRI BUTLER (28921) AUSTRALIAN LABOR PARTY GRIFFITH 33.18
STEVE GEORGANAS (29071) AUSTRALIAN LABOR PARTY HINDMARSH 34.02
CATHY MCGOWAN (23288) INDEPENDENT INDI 34.76

This is really something. The relationship we’re seeing here seems to be these are the seats in which the ALP relies heavily on preference flows from the Greens or Independents to win. The electorate I grew up in is listed here (Richmond) - let’s look at how the votes were allocated.

Richmond_fp <- fp16 %>% 
  filter(DivisionNm == "RICHMOND") %>% 
  arrange(-Percent) %>% 
  mutate(candidate_full_name = paste0(GivenNm, " ", Surname, " (", CandidateID, ")")) %>% 
  dplyr::select(candidate_full_name, PartyNm, DivisionNm, Percent, OrdinaryVotes)

Richmond_fp %>% knitr::kable("simple")
candidate_full_name PartyNm DivisionNm Percent OrdinaryVotes
MATTHEW FRASER (29295) NATIONAL PARTY RICHMOND 37.61 37006
JUSTINE ELLIOT (28987) AUSTRALIAN LABOR PARTY RICHMOND 31.05 30551
DAWN WALKER (28783) THE GREENS RICHMOND 20.44 20108
NEIL GORDON SMITH (28349) ONE NATION RICHMOND 6.26 6160
ANGELA POLLARD (29290) ANIMAL JUSTICE PARTY RICHMOND 3.14 3089
RUSSELL KILARNEY (28785) CHRISTIAN DEMOCRATIC PARTY RICHMOND 1.51 1484

Sure enough - the Greens certainly helped get the ALP across the line.

The interpretation that these seats are the most marginal is incorrect (e.g. imagine if ALP win 30% and the Greens win 30% - that is a pretty safe 10% margin assuming traditional preference flows). But - let’s investigate which seats are the most marginal.

who_won_smallest_margin <- tcp16 %>% 
  filter(Elected == "Y") %>% 
  mutate(percent_margin = 2*(Percent - 50), vote_margin = round(percent_margin * OrdinaryVotes / Percent)) %>% 
  arrange(Percent) %>% 
  mutate(candidate_full_name = paste0(GivenNm, " ", Surname, " (", CandidateID, ")")) %>% 
  dplyr::select(candidate_full_name, PartyNm, DivisionNm, Percent, OrdinaryVotes, percent_margin, vote_margin)

# have a look
who_won_smallest_margin %>%
 head %>%
 knitr::kable("simple")
candidate_full_name PartyNm DivisionNm Percent OrdinaryVotes percent_margin vote_margin
CATHY O’TOOLE (28997) AUSTRALIAN LABOR PARTY HERBERT 50.02 44187 0.04 35
STEVE GEORGANAS (29071) AUSTRALIAN LABOR PARTY HINDMARSH 50.58 49586 1.16 1137
MICHELLE LANDRY (28034) LIBERAL PARTY CAPRICORNIA 50.63 44633 1.26 1111
BERT VAN MANEN (28039) LIBERAL PARTY FORDE 50.63 42486 1.26 1057
ANNE ALY (28727) AUSTRALIAN LABOR PARTY COWAN 50.68 41301 1.36 1108
ANN SUDMALIS (28668) LIBERAL PARTY GILMORE 50.73 52336 1.46 1506

Crikey. We see Cathy O’Toole got in with a 0.04% margin (just 35 votes!)

While we’re at it we better do the opposite and see who romped it by the largest margin.

who_won_largest_margin <- tcp16 %>% 
  filter(Elected == "Y") %>% 
  mutate(percent_margin = 2*(Percent - 50), vote_margin = round(percent_margin * OrdinaryVotes / Percent)) %>% 
  arrange(desc(Percent)) %>% 
  mutate(candidate_full_name = paste0(GivenNm, " ", Surname, " (", CandidateID, ")")) %>% 
  dplyr::select(candidate_full_name, PartyNm, DivisionNm, Percent, OrdinaryVotes, percent_margin, vote_margin)

# Look at the data
 who_won_largest_margin %>%
 head %>%
 knitr::kable("simple")
candidate_full_name PartyNm DivisionNm Percent OrdinaryVotes percent_margin vote_margin
ANDREW BROAD (28415) NATIONAL PARTY MALLEE 71.32 62383 42.64 37297
PAUL FLETCHER (28565) LIBERAL PARTY BRADFIELD 71.04 66513 42.08 39398
JULIE BISHOP (28746) LIBERAL PARTY CURTIN 70.70 60631 41.40 35504
SUSSAN LEY (28699) LIBERAL PARTY FARRER 70.53 68114 41.06 39653
JASON CLARE (28931) AUSTRALIAN LABOR PARTY BLAXLAND 69.48 55507 38.96 31125
BRENDAN O’CONNOR (28274) AUSTRALIAN LABOR PARTY GORTON 69.45 68135 38.90 38163

Wowza. That’s really something. Some candidates won seats with a 30-40 percent margin - scooping up 70% of the two candidate preferred vote in the process!

who_won <- tcp16 %>% 
  filter(Elected == "Y") %>% 
  group_by(PartyNm, StateAb) %>% 
  tally() %>% 
  arrange(desc(n)) 

who_won_by_state <- spread(who_won,StateAb, n) %>% arrange(desc(NSW))

#View data set
who_won_by_state %>% 
knitr::kable("simple")

5.5 Exploring booth level data

The AEC maintains a handy spreadsheet of booth locations for recent federal elections. You can search for your local booth location (probably a school, church, or community center) in the table below.