Module 07 Knowledge Check
5 questions. Pass mark 4 out of 5. Answer every question before checking the answer key below, then retry after reading the feedback.
1. In the grammar of graphics you specify…
- A. a chart type from a list
- B. data, a mapping of columns to visual properties, and a layer
- C. a template and a colour scheme
- D. an axis range and a title
2. Of data, aesthetics, geoms, facets, scales, labels and themes, the only cosmetic one is…
- A. scales
- B. facets
- C. themes
- D. labels
3. A bar chart of group means is a poor choice when…
- A. there are more than three groups
- B. the spread within groups matters
- C. the values are large
- D. the groups have names
4. A chart title should state…
- A. the topic, such as 'Visits by ward'
- B. the finding, such as 'West records the highest visit rate'
- C. the data source
- D. the date range only
5. A bar chart whose axis starts at 380 rather than 0…
- A. contains false numbers
- B. draws a 6% difference as a 4-to-1 one
- C. cannot be exported
- D. is required when values are large
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Answer Key and Explanations
Check these only after attempting every question.
1. B — data, a mapping of columns to visual properties, and a layer
Changing only the geom gives a completely different chart from the same description.
2. C — themes
Everything else changes what the chart claims, which is why theming before the mapping is right is wasted effort.
3. B — the spread within groups matters
Two wards with similar totals had standard deviations of 31 and 42. The bar chart draws two similar bars and hides that entirely.
4. B — the finding, such as 'West records the highest visit rate'
The title is the most-read line. A reader who reads nothing else should still leave with the point.
5. B — draws a 6% difference as a 4-to-1 one
Nothing in the chart is false. Bars encode value as length, and length is read from zero.
Practical Check
Apply this module to your own work: complete the module activity for *ggplot2 Foundations*, then write one sentence naming what your result shows and one naming what it does not.
Strong Answer Pattern
A strong answer names the task, the evidence used, the check performed, and the remaining limitation. It avoids "proved", "guaranteed", or "always" unless the evidence genuinely supports it.