Q1.
Share your observations on this graph. What do you find interesting?
Answer
The graph shows the typical daily sleep of Indians from age 6 to age 75. The second picture is the same data with the vertical axis stretched: it runs from 7.0 to 12.0 hours in steps of half an hour, instead of starting at 0.
- A 6-year-old sleeps about 9.5 to 9.7 hours a day — the highest point on the curve.
- Sleep falls steeply through the teenage years, then more gently, reaching its lowest point of about 8 hours between ages 35 and 40, and staying near 8 hours from about 30 to 50.
- After 50 it climbs again — about 8.5 hours by age 70 and a shade under 9 hours by 75.
- So the curve is a shallow valley — steep down, flat, then a slow climb — and the whole range from highest to lowest is under 2 hours.
Why the curve looks smooth: it holds about 80 points, one for each age, packed close together, so the eye reads them as a curve rather than a chain of segments. Drawn as a column graph the same data would need 70 columns and the gentle valley would be lost in the clutter — this is a case where a line graph is plainly the right choice.
Careful — the two pictures tell different stories: on the first graph, whose axis starts at 0, the line looks almost flat and the change seems tiny. On the zoomed graph, which starts at 7.0, the same dip looks dramatic. Neither graph is lying, but the zoomed one exaggerates. Always check where the vertical axis begins before you judge how big a change is.
Questions worth asking: why do newborns and infants sleep so much? Do people in different countries sleep differently? Do animals show a similar pattern across their lives? The chapter’s point is that a graph should leave you with new questions, not just answers.