Topic A: Representing & Interpreting Data
Lessons 1–5 · Dot plots, histograms, and box plots.
01–03 — Lessons 1–3
Displays of Univariate Data
Represent and compare data sets using statistical displays.
- Dot plot: each value shown as a dot. Good for small data sets.
- Histogram: groups data into intervals (bins). Shows shape.
- Box plot: shows median, quartiles (Q1, Q3), min and max.
- Shape: symmetric, skewed left, skewed right, uniform.
- Outlier: a value far from the rest. Can affect mean significantly.
Box plot shows: min=10, Q1=22, Median=30, Q3=40, max=65. IQR = Q3−Q1 = 18.
Practice — Lessons 1–3
Q1 · Multiple Choice
A histogram with a long tail on the right is described as:
Q2 · Multiple Choice
In a box plot, the 'box' spans from Q1 to Q3. This distance is the:
04–05 — Lessons 4–5
Shape, Center & Spread
- Measures of center: mean (average), median (middle), mode (most frequent).
- Mean: sum ÷ count. Sensitive to outliers.
- Median: resistant to outliers. Better for skewed data.
- Measures of spread: range, IQR, standard deviation.
- Standard deviation (σ): typical distance from the mean.
Data: 2, 4, 6, 8, 10 → Mean = 30/5 = 6 · Median = 6 · Range = 8
Practice — Lessons 4–5
Q3 · Short Answer
Find the mean of: 5, 8, 11, 14, 7.
Q4 · Multiple Choice
A data set has an extreme outlier. Which measure of center is least affected?
Topic B: Two-Variable Data
Lessons 6–9 · Scatter plots, correlation, and lines of best fit.
06–09 — Lessons 6–9
Scatter Plots & Linear Associations
- Scatter plot: plots pairs (x, y) to show association between two variables.
- Correlation: positive (both increase), negative (one increases, other decreases), or no correlation.
- Line of best fit: approximates the trend; used to predict.
- r (correlation coefficient): −1 ≤ r ≤ 1. Closer to ±1 = stronger association.
- Correlation ≠ Causation.
r = 0.95 → very strong positive association. r = −0.2 → weak negative association.
Practice — Lessons 6–9
Q5 · Multiple Choice
A scatter plot shows: as x increases, y decreases. This is a:
Q6 · Multiple Choice
A line of best fit is used to: