The following table shows the average weekly expenditure, in rupees (₹), of three families across categories. What would a cluster-column chart for this data look like?
Step-by-step solution
| Housing | Food | Education | Transportation | Healthcare | Recreation | |
|---|---|---|---|---|---|---|
| Family A | 1940 | 1700 | 1280 | 1200 | 1770 | 535 |
| Family B | 1750 | 1546 | 1500 | 1280 | 1210 | 0 |
| Family C | 950 | 1700 | 1540 | 1400 | 1300 | 150 |
Idea: A cluster-column chart puts related columns next to each other so they can be compared easily. All columns start from 0 on the same scale, so their heights can be read directly.
- Draw a vertical scale for the amount spent, from 0 to 2000 ₹ (the largest value is 1940), and a horizontal axis for the clusters.½ mark
- Choice 1, cluster by category: six clusters (Housing, Food, Education, Transportation, Healthcare, Recreation). In each, draw three columns side by side, one for each family, in a fixed colour per family. For example, the Housing cluster has columns of heights 1940, 1750 and 950.1 mark
- Choice 2, cluster by family: three clusters (Family A, B, C). In each, draw six columns, one per category, in a fixed colour per category. For example, the Family B cluster has columns 1750, 1546, 1500, 1280, 1210 and 0 (no Recreation column).1 mark
- Add a legend telling which colour is which family (Choice 1) or which category (Choice 2), and a title. The two charts are shown in the diagram.½ mark
Check: Every column must start at 0, and Family B’s Recreation column has height 0, so it does not appear.
Answer to write in the exam
Vertical axis: expenditure, 0 to 2000 ₹; horizontal axis: clusters
Choice 1: 6 clusters (categories), 3 columns in each (Family A, B, C)
Choice 2: 3 clusters (families), 6 columns in each (one per category)
Legend for the colours and a title
∴ The chart is either of the two cluster-column charts drawn
Common mistakes that cost marks
- Stacking the columns on top of each other. In a cluster chart the columns stand side by side, each from 0.
- Using different colours for the same family in different clusters, which makes the chart impossible to read.
- Choosing a scale that is too short (for example 0 to 1500), so that the 1940 column does not fit.
How this can come in the exam
In a cluster-column chart with categories as clusters and one column per family, which question is easiest to answer?
- Which family spent the most on food?
- What was Family A’s total spending?
- What fraction of Family C’s spending was on rent?
- Which family spent the least overall?
Show answer
(A) Which family spent the most on food?
The three food columns stand side by side from 0, so comparing them is immediate. Totals and fractions need adding up.
Try one yourself
Three shops sold pens, pencils and erasers: Shop P 40, 25, 10; Shop Q 30, 35, 20; Shop R 20, 30, 15. Describe a cluster-column chart that makes it easy to compare the shops for each item.
Show answer
Cluster by item: three clusters (pens, pencils, erasers), each with three columns, one per shop, on a scale of 0 to 40. For example, the pens cluster has columns 40, 30, 20.
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