Dot Plot Maker
Paste your numbers and get a stacked dot plot with the frequency table worked out beneath it.
What this tool does
A dot plot shows each value in a data set as one dot above its position on a number line, with repeated values stacked. The height of each stack is that value's frequency. In US elementary maths the same diagram is called a line plot; they are the same thing under two names.
Draws one dot per value, stacked where values repeat, above a number line scaled to your data. Alongside the plot you get the count, minimum, maximum, median, mean and mode, plus a full frequency table.
Decimals and negative numbers are handled without being quietly rounded into the wrong column, which is a common failing of simpler generators.
Loads data straight from an uploaded CSV, TSV or plain text file, read on your device and never uploaded, as an alternative to pasting numbers by hand.
Offers four colour palettes, including a colour-blind-safe Okabe-Ito palette and a greyscale option for printing.
How to use it
- Paste or type your values, separated by commas, spaces or new lines.
- Add a title if the chart is going into a report or slide.
- Check the frequency table beneath the plot against your source data - each row shows the count, a bar for the count and the share of the whole set.
- Copy the frequency table as CSV if the next step is a spreadsheet rather than a picture.
- Export as SVG for print or PNG for slides.
Why use this chart maker
For small data sets a dot plot shows every value and its frequency. Counting and stacking by hand is slow, and the frequency table is needed anyway.
Why we built it
We built the dot plot maker to use both names - dot plot and line plot - and to build the frequency table underneath. Summarise the numbers with the mean, median and mode calculator and show spread with the stem and leaf plot generator.
Related tools worth a look: the Cladogram Maker and the Proximity Matrix Calculator.
Who this tool is for
- Maths and statistics students
- Teachers using UK, Australian or US syllabuses
- Anyone showing frequencies of a small data set
When to use it
- Teaching or learning frequency and distribution.
- Comparing small data sets.
- Spotting outliers and gaps.
- Making a worksheet or slide.
Dot plot or line plot?
The terminology splits by country and by level. UK, Australian and New Zealand syllabuses generally say dot plot. US elementary and middle-school curricula say line plot, reserving dot plot for later statistics courses. The diagram is identical.
Confusingly, some statistics software uses "dot plot" for the Cleveland dot plot, which is a different chart - categories down the side with a single dot marking a value. The stacked-dots-over-a-number-line version described here is the one taught in school maths.
Dot plot against histogram
Both show the shape of a distribution, but they differ in what survives. A dot plot keeps every individual value, so you can count exact frequencies and pick out the mode by eye. A histogram groups values into bins, which loses the individual figures but copes with far larger data sets.
| Dot plot | Histogram | |
|---|---|---|
| Individual values | Preserved | Lost inside bins |
| Good up to about | 50 values | Thousands |
| Works with | Discrete or rounded data | Continuous data |
| Gaps between bars | Not applicable | None - bars touch |
| Reading exact frequency | Count the dots | Read the bar height |
A dot plot with fifty values in one stack has stopped communicating. Past roughly fifty observations, a histogram is the better diagram.
What to look for in the shape
Symmetry: if the dots fall away evenly on both sides of the middle, the distribution is roughly symmetric and the mean and median will be close together.
Skew: a long tail to the right is right-skewed, which pulls the mean above the median. A long tail to the left does the reverse. Comparing the mean and median figures beneath the plot is a quick numerical check on what your eye is telling you.
Clusters and gaps: two separated groups of dots suggest two populations mixed together, which usually matters more than any single summary statistic.
Outliers: an isolated dot far from the rest. Investigate it before deleting it - a genuine extreme value is data, while a typing error is not, and a dot plot makes the distinction visible in a way a mean never will.
Dot plot vs scatter plot: one variable or two?
The two look superficially similar - points near an axis - which is exactly why they get mixed up.
A dot plot shows the distribution of a single variable: how one set of measurements - test scores, ages, minutes late - is spread out, clustered or skewed. Every dot is one number's position on one number line.
A scatter plot shows the relationship between two variables, plotting each observation as a pair of coordinates instead of a single position. If your data is one column of numbers, a dot plot is the right diagram, and asking it to reveal a relationship is asking a one-variable diagram to answer a two-variable question. Once you have two matched columns and want to see whether they move together, that question belongs on a scatter plot instead.
What you give it, and what you get back
| Item | Details |
|---|---|
| Input | Numbers separated by spaces, commas or lines. |
| Output | A stacked dot plot with count, min, max, median, mean, mode and a frequency table. |
| Export | Save the chart. |
Issues you may run into
| What you see | Why it happens | What to do |
|---|---|---|
| Stacks are too tall | More than about fifty values. | Use a histogram. |
| Only single dots appear | Values are all unique decimals. | Round them first. |
| A row is skipped | It does not match the expected format. | Check the message listing unreadable lines and fix them. |
Assumptions and limitations
- Suited to about fifty values or fewer. Beyond that, stacks become too tall to count and a histogram works better.
- Values are plotted at their exact positions, so data with many unique decimals produces a plot of single dots with no visible stacking.
- The number line is scaled linearly between your minimum and maximum. Data spanning several orders of magnitude will crowd at one end.
- Axis labels are thinned when there are many distinct values, so not every tick carries a printed number.
- The plot shows distribution only. It cannot show change over time or relationships between two variables.
Frequently asked questions
What is a dot plot?
A dot plot marks each value in a data set with a dot above its position on a number line, stacking dots where a value repeats. The height of a stack is that value's frequency, so the diagram shows both the individual values and the overall shape of the distribution.
What is the difference between a dot plot and a histogram?
A dot plot keeps every individual value and works well up to around fifty observations. A histogram groups values into bins, losing the individual figures but handling thousands of observations. Histogram bars touch because the data is continuous; dots sit at discrete positions.
What is a line plot in maths?
A line plot is the US term for a dot plot - the same diagram of stacked dots above a number line. UK, Australian and New Zealand syllabuses generally use dot plot. Despite the name, no line is drawn through the data.
How do you read frequency from a dot plot?
Count the dots stacked above a value; that count is its frequency. Because every observation is one dot, the total number of dots equals the size of the data set. The frequency table beneath the plot lists these counts.
When should you use a dot plot instead of a bar chart?
Use a dot plot for numerical data that sits on a number line, such as scores or counts. Use a bar chart for categories with no numerical order, such as colours or brands. The give-away is whether the horizontal axis has a meaningful order and spacing.
Can I load data from a file instead of typing it?
Yes. Upload a CSV, TSV or plain text file and it is read directly in your browser - the file is never sent anywhere. Values separated by commas, spaces or new lines are recognised the same way as pasted text.
What is the difference between a dot plot and a scatter plot?
A dot plot shows the distribution of a single variable - one set of numbers spread along a number line. A scatter plot shows the relationship between two variables, plotting each observation as a pair of coordinates. One column of numbers calls for a dot plot; a relationship question between two measurements needs a scatter plot instead.