The Sixty-Second Chart Read: a Ten-Question Checklist for Any Chart

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Opens on Chapter 1’s example: Marisol’s vendor chart: delivery times of 3.4 and 3.1 days, drawn on bars that start at 3.0.

Two numbers off the chart

First value

Second value

Where the axis starts leave blank if zero

A survey or poll behind it?

How many were asked optional

Load another example from the book

The ten questions (Chapter 24)

1. What’s the claim? Say it in your own words with two numbers; does your own sum agree? (Chapter 1)

Answer

2. What’s measured, and in what units? Visits or visitors? Thousands or millions? Dollars or percent? (Chapters 1–2)

Answer

3. Where does the axis start, and what is one step worth? Bars must start at zero; check the ticks are evenly spaced and how stretched the picture is. (Chapters 2, 6, 7)

Answer

4. Is it the right kind of picture? Bars for amounts, lines for time; no swollen pictures, 3-D slices or misread log scales. (Chapters 3, 9, 10)

Answer

5. Percent or points? Count or rate? “Up 5%” and “up 5 points” differ; a bigger place has more of everything. (Chapters 4, 5)

Answer

6. Who chose the window? Would another start date, or per-month amounts instead of a running total, tell another story? (Chapters 11, 12)

Answer

7. What’s hiding behind the average or the map? The spread behind an average; a map of counts shows where people live. (Chapters 13, 14)

Answer

8. Relative or absolute? How many were asked? “Doubles” from what to what? How many in the sample, and what margin? (Chapters 16, 17)

Answer

9. Compared to what? A second axis, old dollars, a short record, two things that both grew. (Chapters 8, 15, 18, 19)

Answer

10. Is it a forecast, an ad or a rank? Find the range, the typical case and the scores behind the ranks. (Chapters 20–22)

Answer

Enter your numbers, then press Calculate.

How it works

Questions 1–3 take ten seconds each and catch most tricks: say the claim with two numbers, check the units, and look at where the axis starts. If the bars start above zero, the bars you see are (value − start) long, so the tool shows how many times bigger one looks against how many times bigger it is. A poll’s margin of error is about 1 ÷ √n at its widest: 100 ÷ √n percentage points.

From the book, Chapter 1. Marisol’s vendor chart: 3.4 → 3.1 days is a drop of 0.3 days, 8.8%, yet bars from 3.0 are 0.4 and 0.1 tall: one looks 4 times the other. In Chapter 24 the renewal chart’s 88 and 94, drawn from 85, look 3 times apart; the real ratio is 1.068. Five riders give a margin of about ±45 points. Every chapter and its calculator →

Rounding is half up, the way the book rounds. Numbers can be typed as 1,450, $38, 12% or 2.5 million. Everything stays in your browser: no sign-up, nothing stored or sent.