Problem set 2

Data visualization with {ggplot2}

Due by 23:59 on Monday, September 14, 2026

Purpose

Chapter 2 of ModernDive introduces the grammar of graphics, or the idea that any statistical plot consists of variables in data that are mapped to aesthetic attributes of geometric objects. You learned how to use ggplot() to create five common plot types, or the “5NG”: scatterplots, linegraphs, histograms, boxplots, and barplots.

In this problem set, you’ll practice making some plots with ggplot(). By the end, you should be able to:

  • Name the data, aes, and geom components of ggplot() code and explain what each one means
  • Predict what happens when a constant aesthetic (like alpha = 0.25) is placed inside aes() instead of outside it
  • Create a scatterplot, a linegraph, a histogram, and barplot
  • Explain when to use geom_bar() versus geom_col() based on whether your data is pre-counted

Criteria for success

This problem is graded using a ✔+/✔/✔− system. I’m looking for correct plot-building logic and genuine attempts at the short written answers, not polished prose.

  • ✔+: All plots render without errors and use the correct variables, aesthetics, and geoms. The written answers correctly name the grammar of graphics components, correctly predict the aes(alpha = ...) bug, and give a real justification for the geom_bar() vs. geom_col() choice (i.e. you shouldn’t just say “the chapter said so”). The extension does fun, neat things and goes beyond the bare minimum.
  • ✔: This is the expected level of performance. All plots run and mostly use the right geoms and variables; minor mismatches (e.g., a slightly-off bin width) are fine. Written answers are attempted and reasonable.
  • ✔−: Plots are missing, don’t render, or use the wrong geom for the variable types involved (e.g., a histogram for a categorical variable). Written answers are left blank.

You may work together in groups of up to four, but you must turn in your own answers and note who you worked with.

And remember: everything human-facing must be human-generated. Don’t submit AI-generated text. I want to hear your voice.

Also, if you do use LLMs to help with the code (I recommend not!), make sure you follow the guidelines from the syllabus about how to cite what you use.

How to submit

Submit a single rendered PDF on Canvas.

Instructions

  1. Download this .zip file. Make sure you unzip or extract it after you download it! Open the unzipped folder in Positron.

  2. Rename the Quarto file named your-name_problem-set-2.qmd to something that matches your name.

  3. Complete the tasks given in the Quarto file. You can definitely copy, paste, and adapt from other code in the document—don’t try to write everything from scratch!

  4. When you’re all done, render the document to Typst (pdf), PDF, or Word. Upload that file to Canvas. Do not upload a rendered HTML file (they don’t work on Canvas).