stat4arch

Petr Pajdla & Peter Tkáč

AES_707: Statistics seminar for archaeologists

Course info

Seminar 1

17. 2. 2022

Today:

  • Introduction to quantitative methods in archaeology.
  • Introduction to the R programming language and environment.
  • Data organization and tidy data.

Quantitative methods in archaeology

Maths and archaeology? Why?

(brainstorming)

R programming language

What is R?

  • Scripting language and environment for statistical computing and graphics.
  • Open source, free software.
  • Alternatives: Python, SQL, JavaScript etc.
  • Clicking alternatives: Statistica, PAST etc.

https://www.r-project.org/
https://cran.r-project.org/

RStudio

  • IDE (Integrated Development Environment) for R (supports also other languages).

RStudio is a set of integrated tools designed to help you be more productive with R. It includes a console, syntax-highlighting editor that supports direct code execution, and a variety of robust tools for plotting, viewing history, debugging and managing your workspace.

https://rstudio.com/

RStudio IDE

  • Editor is where you view and edit your scripts.
  • Console shows the output after you execute the code.
  • Environment lists available objects.

And much more…

Console

R version 4.1.2 (2021-11-01) -- "Bird Hippie"
Copyright (C) 2021 The R Foundation for Statistical Computing
Platform: x86_64-pc-linux-gnu (64-bit)
*
R is free software and comes with ABSOLUTELY NO WARRANTY.
You are welcome to redistribute it under certain conditions.
Type 'license()' or 'licence()' for distribution details.

  Natural language support but running in an English locale

R is a collaborative project with many contributors.
Type 'contributors()' for more information and
'citation()' on how to cite R or R packages in publications.

Type 'demo()' for some demos, 'help()' for on-line help, or
'help.start()' for an HTML browser interface to help.
Type 'q()' to quit R.

>

R is a smart calculator

2 + 40

[1] 42

((2022 * 2) - 1 / (40 + 2)^3) / 2

[1] 2022

round(6.48^2)

[1] 42

sqrt(1764)

[1] 42

8 * 10^10

[1] 8e+10

Console

  • Console evaluates the input immediately after hitting Enter and returns the output.

Script

  • Script documents the code, i.e. the sequence of commands.
  • Script is a plain text document.

ctrl + enter send line of code from script to console

Notion of functions and objects

Object

  • Everything is an object.
  • Contains data.
  • Some objects are already populated with something…
pi

[1] 3.141593

pi + 1

[1] 4.141593

Function

  • Ends with parentheses.
    function-name(args...)
  • Arguments go in the parentheses.
  • Does something.
round(x = pi)

[1] 3

round(x = pi, digits = Inf)

[1] 3.141593

Data, databases and data organization

What is database?

(Brainstorming)

Relational database - basic terms

Relational database - basic terms

  • variable (proměnná / atribut) - napr. hmotnosť keramického fragmentu
  • observation / object (entita / záznam) - napr. konkrétny keramický fragment
  • value (hodnota)
  • primary key / unique ID (primární klíč)

Tidy data

Types of variables

Categorical

  • dichotomies (dichotomická) - prítomnosť alebo neprítomnosť nejakého javu (“Y/N”)
  • nominal (nominální) - archeologické datovanie (“neolit”), číslo objektu, keramický typ
  • ordinal / rank (ordinální, pořadová) - tlupa / kmeň / náčelníctvo / štát, alebo: komponenta / sídelný areál / nadkomunitný areál

Numeric

  • discrete (diskrétní) - môžu byť len celé čísla - napr. počet lokalít, počet bronzových spôn

  • continuous (spojité / metrické) - môže byť akékoľvek reálne číslo - hmotnosť ker. fragmentu, dĺžka železného meča

  • interval (intervalové) - numericky vyjadrujú vzdialenosť na vyjadrenie hierarchického vzťahu, nemajú ale zmysluplný nultý bod, umožňujú relatívne porovnávanie ale nie kalkulácie (napr. BC/AD - rozdiel medzi 400AD a 800AD je 400 rokov, 400AD ale nieje 2 krát staršie než 800AD )

  • ratio (poměrové) - na rozdiel od intervalových premenných umožňujú kalkulácie (napr. vek - objekt starý 1000 rokov je 2krát starší než objekt starý 500; dĺžka meča,…)

Tidy data

What's wrong?

Basic tidy data principles

  • one variable in one column
  • one observation in one row
  • one value in one cell
  • backup your data!
  • be consistent!

https://kbroman.org/dataorg/