1The Whole Strip Is 100%
A strip graph represents an entire set of survey data as one long strip. The whole strip stands for 100%, and each category is cut to a length matching the share it represents. It's a lot like cutting colored tape into pieces sized to how much you like each thing, then lining them up side by side.
2Percentage Is (Part) ÷ (Whole) × 100
If 8 out of 20 people like summer, you find the percentage by dividing 8 by 20 and multiplying by 100.
The people who like summer make up 40% of the whole group.
3The Strip's Length Matches the Percentage
In a pie chart, a percentage turns into a central angle (in degrees), but in a strip graph, a percentage turns directly into the strip's length. If you think of the whole strip's length as 100, a category that's 40% takes up 40% of the strip's total length.
If you draw the strip 10 cm long, the section representing summer is 4 cm long.
On the activity page's table, check that adding up every category's percentage gives 100%, and that the lengths you measure with a ruler add up to the strip's total length.
4How Is It Different From a Pie Chart?
A strip graph and a pie chart run on exactly the same principle. Turn the percentage into an angle, and you get a pie chart; turn it into a length, and you get a strip graph. But a strip graph is especially good for lining up several sets of data side by side and comparing their lengths as if with a ruler, so when the same survey is repeated over time (say, last year versus this year), stacking several strips one above another lets you compare the changes at a glance.
5Try Playing With It Like This
- Increase the number of people in one category. Watch how both its length in the strip and its percentage grow together.
- Set every category to the same number of people. Check that all four categories come out to exactly 25% each, and that the strip splits into exactly four equal parts.
- Switch back and forth with the pie chart page. Compare how the same data feels different when you see it as wedges versus as a strip.