Title: Watch: From chart to decision
Course: Advanced Data Science: A Graduate Course > Section: Module 3: Exploratory analysis, visualization, and the stakeholder story

Watch

▶ Recorded lecture (~25 min) + slides ↓:
- The difference between a chart and a decision: a chart displays data, a decision needs one comparison, framed against an alternative, that a manager can act on this week. We rewrite three “pretty” charts into the one question each should answer.
- Encoding and preattentive attributes: why position and length are read fastest and most accurately, why area and angle are read poorly, and how to spend the reader’s attention on the comparison that matters.
- Color used honestly: sequential hue for ordered magnitude, a single highlight color for “look here,” categorical hue only for true categories, and why a rainbow scale invents structure that is not there.
- The principle of proportional ink and misleading axes: the ink (bar length, area) must be proportional to the quantity; truncated baselines, dual y-axes, and inconsistent bins are the most common ways honest people mislead.
- Stating uncertainty in words: translating a confidence interval or a small sample into a sentence a non-technical person can repeat, and refusing false precision.
- The one-sentence takeaway title: how writing the title first (“East side sales grew twice as fast”) forces the figure to earn its place or be cut.

“Advanced Data Science by Michelle Blomberg is licensed under CC BY-NC-SA 4.0.”