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Majority

Source: vignettes/articles/majority.rmd
majority.rmd


This article explores the majority dataset and its potential uses.

Majority

The majority dataset contains the winning candidate and the margin of victory by electorate. The majority is calculated by subtracting the number of votes of the winning candidate form the number of votes of the second candidate. The margin of victory divides this number by the total votes cast to create a percentage figure.

Upload data

View the shape of data frame.

# Load dataset
df <- scgUtils::get_data("majority")
head(df)
Election Electorate Party Candidate Votes Percentage Party_List
2023 Auckland Central Green Party SWARBRICK, Chloe Charlotte 3896 11.31 Yes
2023 Banks Peninsula National Party WEENINK, Vanessa 396 0.81 Yes
2023 Bay of Plenty National Party RUTHERFORD, Tom 15405 34.57 Yes
2023 Botany National Party LUXON, Christopher 16323 44.69 Yes
2023 Christchurch Central Labour Party WEBB, Duncan 1841 4.75 Yes
2023 Christchurch East Labour Party DAVIDSON, Reuben John 2397 6.25 Yes


Update electorate names

Update of the names of electorates so that they can be traced back through name changes.

# Convert pre-2020 electorate names to match name changes that occurred in 2020 and view
df <- update_names(df, output = "electorate")
head(df)
Election Electorate Party Candidate Votes Percentage Party_List
2023 Auckland Central Green Party SWARBRICK, Chloe Charlotte 3896 11.31 Yes
2023 Banks Peninsula National Party WEENINK, Vanessa 396 0.81 Yes
2023 Bay of Plenty National Party RUTHERFORD, Tom 15405 34.57 Yes
2023 Botany National Party LUXON, Christopher 16323 44.69 Yes
2023 Christchurch Central Labour Party WEBB, Duncan 1841 4.75 Yes
2023 Christchurch East Labour Party DAVIDSON, Reuben John 2397 6.25 Yes


Add type of electorate

Add a column of the electorate type to filter out Maori electorates.

# Add Electorate Type and filter for General electorates only and view
df <- add_data(df, output="type")
head(df)
Electorate Election Party Candidate Votes Percentage Party_List Electorate_Type
Auckland Central 2023 Green Party SWARBRICK, Chloe Charlotte 3896 11.31 Yes General
Auckland Central 1999 Labour Party TIZARD, Judith Ngaire 5285 16.19 yes General
Auckland Central 2005 Labour Party TIZARD, Judith Ngaire 3884 10.79 Yes General
Auckland Central 2011 National Party KAYE, Nicola Laura 717 2.16 Yes General
Auckland Central 2020 Green Party SWARBRICK, Chloe Charlotte 1068 3.00 Yes General
Auckland Central 1996 Labour Party TIZARD, Judith Ngaire 3353 10.03 Yes General


Plot

Create a parallel coordinates plot to track and visualise how electorates have changed hands and their margins increase or decrease across all MMP elections.

df %>%
  filter(Electorate_Type == "General") %>%
  # Remove electorates that had fewer than 7 elections
  group_by(Electorate) %>%
  mutate(No. = length(Electorate)) %>%
  ungroup() %>%
  filter(No. >= 7) %>%
  mutate(Percentage = ifelse(Party %in% c("Labour Party", "Green Party",
                                          "Alliance", "Jim Anderton's Progressive"),
                             -Percentage, Percentage)) %>%
  ggplot(aes(y=Percentage, x=reorder(Election, -Election), group=Electorate, colour=Party)) +
  geom_hline(yintercept = 0, colour = scgUtils::colour_pal("Regent Grey"),
             linewidth = 0.5, linetype = "dashed") +
  geom_smooth(method = "loess",formula = 'y ~ x',
              colour = scgUtils::colour_pal("French Grey"),
              span = 0.3, se = FALSE, alpha = 0.25, linewidth = 0.25) +
  geom_point(shape='\u6c', size=4) +
  scale_y_continuous(limits = c(-70,70), expand = c(0,0), position = "right",
                     breaks = c(-60,-40,-20,0,20,40,60),
                     labels = c("+60","+40","+20","0","+20","+40","+60")
  ) +
  scale_x_discrete(expand=c(0,0)) +
  scale_colour_manual(values = scgUtils::colour_pal("polNZ")) +
  labs(title = "Margin of Victory (%) by General Electorate\nOver Time (1996 - 2023)",
       caption = "\n\n*Includes electorates which existed at 7 or more elections only",
       y = "",
       x = "") +
  coord_flip(clip = "off") +
  scgUtils::theme_scg() %+replace%
  theme(legend.position = "none",
        panel.grid.major.y = element_blank(),
        panel.grid.minor = element_blank(),
        axis.line = element_blank(),
        axis.ticks = element_blank(),
        axis.text.x.top = element_text(vjust = 4)
  )