Interpret column graphs & tables
Theory
To read a column graph, find a category and read straight across from the top of its column to the scale. Add every column for a total, and subtract two values to see “how many more”.
To interpret a column graph is to read values and compare them.
The value of a column is its height: read straight across from the top of the column to the number on the scale.
The tallest column is the most; the shortest is the least.
A total adds every column; a difference (“how many more”) subtracts one value from another.
Always check the size of one step before reading a value.
| Gridlines | One step | Halfway is |
|---|---|---|
| 0, 1, 2, 3 | \(1\) | a half |
| 0, 2, 4, 6 | \(2\) | an odd number |
| 0, 5, 10 | \(5\) | a multiple of \(5\) |
How to interpret a column graph
- Check the size of one step on the scale.
- Find the category, then read across from the top of its column.
- Add every column for a total.
- Subtract two values to compare — “how many more”.
Read across from the top of the Tuesday column.
| Tuesday | \(=\) | \(6\) |
Add every column.
| \(4+6+2+8+6\) | \(=\) | \(26\) |
The most is the tallest column.
| \(8>6>4>2\) | Thursday |
Take the smaller value from the larger.
| \(8-4\) | \(=\) | \(4\) |
Common pitfalls
Frequently asked questions
How do I read a value from a column?
Read straight across from the top of the column to the scale. The number it lines up with is the value.
What if the top is between two gridlines?
Use the size of one step. If gridlines are \(2\) apart, a top halfway between them is an odd number such as \(5\).
How do I find the total?
Add the value of every column. A total needs them all, not just the tallest one.
How do I answer 'how many more'?
Subtract the smaller value from the larger. It is a difference, so you do not add the two columns.
Which column shows the most?
The tallest column. Its height is the largest frequency, so it stands for the most.