---
title: "Session 1 — Vectors (world population)"
subtitle: "QSS 1.3.5 | Probability and Statistics (MIR)"
author: "Prof. Dae-Jin Lee (daelee@faculty.ie.edu)"
date: "Fall 2026"
output:
  html_document:
    toc: true
    toc_float: true
    theme: flatly
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE, message = FALSE, warning = FALSE)
```

World population series from the QSS intro vignette.

```{r}
world.pop <- c(2525779, 3026003, 3691173, 4449049, 5320817, 6127700, 6916183)
world.pop

world.pop[2]
world.pop[c(2, 4)]
pop.million <- world.pop / 1000
pop.rate <- world.pop / world.pop[1]

pop.increase <- world.pop[-1] - world.pop[-7]
percent.increase <- (pop.increase / world.pop[-7]) * 100
percent.increase

length(world.pop)
min(world.pop)
max(world.pop)
range(world.pop)
mean(world.pop)

year <- seq(from = 1950, to = 2010, by = 10)
names(world.pop) <- year
world.pop
```

**Interpret:** `mean(world.pop)` is a descriptive summary across these years — not a causal claim.