Statistics · Histograms
Chapter 1 · 3
The idea
Interpreting histograms
Getting information back out of a histogram — a frequency is an area, so part of a class is the matching proportion of a bar's area. Why that rests on values being spread evenly within a class (and is therefore an estimate), and how to read off a total, a mean, the median class, a range that cuts across class boundaries, and a comparison of two groups.
A full journey — read it, play with it, work it, then earn real exam marks. Everything stays on the timeline below.
In this lesson — start anywhere
Statistics · Histograms
Interpreting histograms
Getting information back out of a histogram — a frequency is an area, so part of a class is the matching proportion of a bar's area. Why that rests on values being spread evenly within a class (and is therefore an estimate), and how to read off a total, a mean, the median class, a range that cuts across class boundaries, and a comparison of two groups.
Why it works
Reading turns areas back into frequencies
Building a histogram turns frequencies into areas. Reading one turns areas back into frequencies. That is the whole of this page. The height of a bar is the frequency density, soand every question below is secretly the same question: which area am I being asked for?
Here is the histogram we will read all the way through. It shows the times, in minutes, that people took to finish a task.
Keep reading — free
The rest of the explanation, plus 3 worked examples you step through move by move.
Start freeTakes a minute — no card.