Histogram

A histogram shows how the values in a column of numbers are spread out: it cuts them into ranges of equal width and draws one bar per range, as tall as the number of values that fall in it.

Select any words here to ask your Maestro about them.

With 20-minute bars, every order lands in the same bar. What do you think happens with 3-minute bars?

180 delivery orders from a taco shop. Same data in every view; only the width of the bars changes.

What it's for: seeing the shape of a column of numbers before you sum it up with an average. At a glance you see where the values bunch up, how spread out they are, whether two groups are mixed together, or whether a long tail of big values is pulling things.

To read one: each bar is a range (20 to 25 minutes, say), and its height tells you how many values fall in it. The bars touch because the axis is continuous; in a bar chart of categories they stand apart.

You pick the bar width, and it changes what you see: too wide hides groups, too narrow draws noise. Start with about 10 bars, then try narrower and wider: little data wants fewer bars, thousands of rows want more. If one value sits far from the rest, check whether it's an outlier.

You practice it step by step, with real data, in How do I draw and read a histogram of a numeric column?.

How it's used

Ticket per order · 160 orders

Most orders cost between $150 and $400, but the tail stretches to the right: a few big orders. With that shape the average lands above what a typical customer pays; the median describes it better.

When to look closer

Where does the first bar start?

Same width, same 45 orders. Can the shape change if the bars start somewhere else?

Ask your Maestro about Histogram

It answers from the free course page closest to this word, the way it answers while you study.

Example

You: What does "Histogram" mean, in plain words?

Your Maestro: I'll explain it with a case of yours: it sticks better than a definition. Which column in your data would you like to see as a histogram?

Asking about: Answers from the page "How do you know if the number an AI gave you is right?"

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Learn more

Histogram on Wikipedia

Box plot
A box plot sums up a variable in five numbers: the minimum, the first quartile, the median, the third quartile and the maximum. The box runs from the first to the third quartile and holds the middle half of the data.
Outlier
An outlier is a value that sits far from the rest, like a $9,800 order among $300 ones. It can be a data-entry error or a real, important case: before you drop it, find out which.
Scatter plot
A scatter plot draws one dot per case, with one variable on each axis, to show whether two numbers move together: when one goes up, does the other go up, go down, or do nothing?

The whole glossary