MAT 241: Introduction to Data and Quarto

Dr. Gilbert

January 2, 2026

Playing Along

Please play along…

  1. Open RStudio
  2. Ensure that you are in your MAT241 project by checking the top-right corner of your RStudio window (you should see your project name next to that translucent blue cube.)
  3. Create an empty Quarto Document in RStudio by navigating to File -> New File -> Quarto Document... using the menus.
  4. Choose to Create Empty Document and then remove the minimal YAML header to start with a truly empty document.
  5. Navigate to this Day 2 to 5 Activity notebook.
  6. Copy all of the lines in that document and paste them into your Quarto document, making sure that you are in the Source editor rather than the Visual editor.
  7. Save that file to a convenient location on your computer.
  8. Play with that file as we work through these slides together.

Working in Quarto

Quarto documents allow you to mix narrative and data analysis all in one document, outputting multiple formats including HTML, Word Document, PDF, slides, and more.

You’ll be asked to work in Quarto for your two practical exams and we’ll spend our first few class meetings in the Quarto environment as well.

Quarto documents consist of the following components.

  1. The YAML header is at the top of the document, between “code fences” (---).

    • You should feel free to make edits, but note that YAML is very picky. Please update the author: and choose a different theme: if you’d like.

  2. Code chunks are opened and closed with triple back-ticks, followed by curly braces and the name of the language you are writing in (for our class, that will be r.

    • In order to create a new code cell you should use the +c button and choose R as the option or you can use the keyboard shortcut Option + Command + I (mac) / Ctrl + Alt + I (Windows).

  3. Text blocks permit you to write text freely, using markdown shortcuts and HTML to format your text. You may alternatively use the Visual Editor if you prefer a more familiar click-button interface.

Running Code in Quarto

As you are creating a Quarto document, it will be convenient to run your code and ensure that it works as expected.

  • With your cursor on a line inside of a code chunk, you can run that line of code by holding command (mac) or ctrl (Windows) and hitting the Enter/Return key.
  • You can run an entire code chunk by using the green “play” button in the top-right corner of the code chunk.

Warnings: Below are a couple of warnings to give you a heads-up on some common issues.

  1. You must have a blank line before and after the triple back-ticks opening and closing a code chunk.

  2. You can’t “run” the lines with the triple back-ticks on them.

  3. Code flows like a river – downstream code (code lower in your document) is only aware of code that exists and has been run upstream (earlier in your document).

  4. You can render your entire document, which includes running all the code in it, by using the blue Render arrow at the top of your editor.

    • Rendering is not how you should typically run your code, but you should do it once in a while to ensure that your code flows as you intended.

  5. Coding is finicky – you’ll experience errors (often showing as red text in the console). That’s natural, it happens to everyone, and I’m here to help!

Rendering Your Notebook and Running Code

We’ll save writing and executing code for our next meeting, choosing to focus on text today.

Before we do though, complete each of the following.

  1. Use the blue Render arrow to render your document to the HTML output. If it opens in a new window, use the settings gear icon and check that you’d like to Preview in Viewer Pane rather than Preview in Window. Render once again.
  2. Click on the Environment tab in the top-right pane of RStudio. Then, move your cursor to line 13 of the Quarto document and run each of the three lines in that code chunk.

Text Blocks in Quarto

You have two choices regarding how your Quarto editor looks – the Source editor or the Visual editor.

These are toggled from the top-left corner of the editor window.

  • The source editor may be less comfortable at first, but using it will allow you to be much faster in the long-run.
  • The visual editor provides a slightly more familiar interface with formatting buttons you can use rather than needing to remember markdown syntax.

The choice of which to use is yours.

Goals for Today

We’ll use what you learned in the Topic 1 notebook, providing an introduction to data and data types to classify variables from the Austin Zillow data set.

Consider the following reminders:

  • Observations are the units from which data were recorded.

    • Observations often appear as rows in tabular data frames.

  • Variables are the characteristics being measured about each observation.

    • Variables often appear as columns in tabular data frames.

  • Variables can be numerical, categorical, or neither. In this course, we’ll refer to the latter category as unique identifiers.

    • Numerical variables are variables for which measures like an average (ie. a mean) are meaningful.
    • Categorical variables are variables which serve to group observations into categories.
    • Unique identifiers are non-numeric variables with no grouping benefit.

Tasks

Navigate down to line 43 of the Quarto document. There, you’ll not that we’re going to fill in a data dictionary for the Zillow Dataset.

Work with the people around you to address each of the following.

  1. Prior to the sub-heading on numerical variables add a sentence describing how many observations and how many variables are contained in the Austin Zillow data set. Include a short discussion about how you found this information.
  2. In the subsection on numerical variables, identify each of the numerical variables in the data set and update the bulleted list to include them. Talk with eachother about what surrounding text with a single asterisk, two asterisks, or backticks does.
  3. Similarly, update the bulleted list for the categorical variables and the unique identifiers.
  4. While you are working, discuss some interesting questions that you might be able to ask and answer using the data in the Austin Zillow data set.

Exit Ticket Task

Navigate to our MAT241 Exit Ticket Form, answer the questions, and complete the task below.


Note. Today’s discussion is listed as 1. Intro to Data

Task: Provide at least one question you’d be interested in answering with our available Austin Zillow data.

Closing

  1. Render your notebook and make sure that the sections we’ve updated look as you intended them to.

    • Make any updates you like and re-render the notebook.

  2. We got a first taste of writing in a Quarto document today, and we’ll continue to learn more.

  3. Homework: Complete and submit the Topic 2 notebook by 11:59PM on Sunday, January 11. This notebook will give you a first introduction to using R.

    • Be sure to see me immediately if you are having difficulty with setup.