polls_tv.Rmd

---
title: "Regression and Other Stories: Death penalty poll"
author: "Andrew Gelman, Jennifer Hill, Aki Vehtari"
date: "`r Sys.Date()`"
output:
  github_document:
    toc: true
---
Tidyverse version by Bill Behrman.

Death penalty poll - Proportion of American adults supporting the death
penalty. See Chapter 4 in Regression and Other Stories.

-------------

```{r, message=FALSE}
# Packages
library(tidyverse)

# Parameters
  # Gallup death penalty poll data
file_death_penalty <- here::here("Death/data/polls.dat")
  # Common code
file_common <- here::here("_common.R")

#===============================================================================

# Run common code
source(file_common)
```

# 4 Statistical inference

## 4.2 Estimates, standard errors, and confidence intervals

### Comparisons, visual and numerical

Data

```{r, message=FALSE}
death_penalty <- 
  file_death_penalty %>% 
  scan() %>% 
  matrix(ncol = 5, byrow = TRUE) %>% 
  as_tibble(
    .name_repair = ~ c("year", "month", "favor", "not_in_favor", "no_opinion")
  ) %>% 
  transmute(
    date = lubridate::make_date(year = year, month = month),
    favor = favor / (favor + not_in_favor),
    favor_sd = sqrt(favor * (1 - favor) / 1000)
  )
```

Are you in favor of the death penalty for a person convicted of murder?

```{r}
death_penalty %>% 
  ggplot(aes(date, favor)) +
  geom_pointrange(
    aes(ymin = favor - favor_sd, ymax = favor + favor_sd),
    size = 0.2
  ) +
  scale_x_date(
    breaks = lubridate::make_date(year = seq(1940, 2000, 10)),
    minor_breaks = lubridate::make_date(year = seq(1936, 2004, 2)),
    date_labels = "%Y"
  ) +
  scale_y_continuous(labels = scales::label_percent(accuracy = 1)) +
  labs(
    title = 
      "Are you in favor of the death penalty for a person convicted of murder?",
    x = "Year",
    y = "Percentage in favor of those with an opinion",
    caption = "Source: Gallup"
  )
```