Highlighting and small multiples
To answer one question about one series, highlight it and keep the others grey for context. To compare groups side by side, use small panels that share the same axis.
Highlight one trajectory (W6 p. 24). Question: did course C1's activity increase from week 1 to week 4? Draw C1 in a strong colour and the other seven courses in light grey for context. C1 moves from 5.0 to 5.2: change +0.2 logins per student, relative change 0.2/5×100 = +4%. One question, one highlighted series; the context lines show whether C1's movement is unusual. C1 also rises and falls between those weeks, so a +0.2 endpoint change should be described as small, not as a clear trend.
Small multiples on a common scale (W6 p. 25). Give each course its own panel with identical axes (all 0-10). Because the scales match, positions are comparable across panels: at week 4, C1 = 5.2 and C4 = 5.8, a difference of 0.6. If each panel chose its own y-range, a 0.2 change could fill a panel and look as dramatic as a much larger change elsewhere; independent scales must be labelled prominently and should not be used for cross-panel comparison.
Source: W6 PDF pp. 1-37. Most numbers in the lecture are illustrative or constructed for teaching; pp. 26-27 reuse the Week 5 synthetic registration counts. The Week 6 lab manual (L6) practises Week 5 EDA reasoning and is worked through section by section in Lab work.
Practice problems
Supplementary study questions on the lecture concepts — not verbatim exam questions. Each answer counts toward spaced review.
1. Conceptual understanding
Definitions and distinctions.
C1 moves from 5.0 to 5.2 logins per student. What is the relative change?
Why do the small-multiple panels share the range 0–10?
2. Application
Apply the concept to a case or calculation.
Why keep the other seven courses visible in grey?
C1 goes from 5.0 to 5.2 and rises and falls in between. How should it be described?
3. Interpretation and limitations
Evaluate assumptions and justify conclusions.
At week 4, C1=5.2 and C4=5.8 on shared 0–10 panels. What is the difference?
What is the danger of each panel having its own y-range?
Explain it in writing
Self-checked, not marked. Write a few sentences, then compare with the example answer. Your writing is saved as you type.
Show an example answer
Absolute change = 5.2 − 5.0 = +0.2 logins per student. Relative change = 0.2/5.0 × 100 = +4%.
Check: did you answer the question, use evidence or working, and avoid claiming more than the evidence supports?
Show an example answer
The same position must mean the same value in every panel. With separate ranges, a small change in one course could look as large as a big change in another.
Check: did you answer the question, use evidence or working, and avoid claiming more than the evidence supports?