---
title: "Session 5 — Nonlinearity"
author: "Prof. Dae-Jin Lee (daelee@faculty.ie.edu)"
output: html_document
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE, message = FALSE, warning = FALSE)
library(tidyverse)
ci <- read_csv("data/country_indicators.csv")
```

```{r}
ci |> summarise(
  r_level = cor(gdp_per_capita, life_expectancy),
  r_log = cor(log(gdp_per_capita), life_expectancy)
)

ggplot(ci, aes(gdp_per_capita, life_expectancy)) +
  geom_point() + geom_smooth(se = FALSE)

ggplot(ci, aes(log(gdp_per_capita), life_expectancy)) +
  geom_point() + geom_smooth(method = "lm", se = FALSE)
```