Statistics Foundation · Lesson 2.5
Comparing groups descriptively.
Descriptive comparison brings together centre, spread, shape, quartiles, boxplots and careful interpretation. This lesson teaches students how to compare groups honestly, recognise overlap and variability, and avoid making unsupported causal claims from descriptive statistics alone.
105–110 minute lesson plan
Learn how to compare groups without oversimplifying the data.
This lesson completes Module 2 by combining everything learned so far. Students compare groups using centre, spread, shape, quartiles and outliers. The main goal is not only to identify differences, but to describe those differences honestly.
0–10 min
Why group comparison matters
Understand that descriptive statistics often become more meaningful when we compare two or more groups carefully.
10–25 min
Compare centres
Use means and medians to compare typical values, while checking whether those summaries are appropriate for the data shape.
25–45 min
Compare spread
Compare range, IQR and standard deviation to decide which group is more consistent or more variable.
45–65 min
Compare shape
Look for skewness, clusters, long tails and outliers. Two groups may have similar centres but very different shapes.
65–90 min
Interactive comparison lab
Adjust group differences, spread, skewness and outliers to see how descriptive comparisons change.
90–110 min
Careful reporting
Practise writing cautious descriptive comparisons without making unsupported causal claims.
Mastery checklist
By the end, you should be able to compare groups responsibly.
Compare group centres using means or medians.
Compare group spread using standard deviations or IQRs.
Identify when groups have similar centres but different variability.
Use boxplots and dot plots to compare distributions visually.
Recognise skewness, clusters and outliers across groups.
Discuss overlap between groups.
Avoid unsupported causal conclusions.
Write clear descriptive comparison paragraphs.