Take it and use it
StatsCapybara is not merely free to read. It is openly licensed, which is a stronger and more useful promise: you may copy it, change it, translate it, print it, build on it and teach from it, without asking and without paying. This page says what the licenses are and how to credit the source.
The short version. The teaching material is under CC BY 4.0. The code that runs the site is under the MIT license. Credit Hakan Karsilar and StatsCapybara, link back, say if you changed something, and the rest is yours.
The two licenses
A site like this is two different things wearing one coat, and they want different licenses. The prose, the questions and the datasets are creative and educational work, so they take a Creative Commons license. The scripts that draw the visualizations are software, so they take a software license.
| Part | License | What that covers |
|---|---|---|
| Content | CC BY 4.0 | Lesson prose, common questions, glossary definitions, quiz and check questions, the 71 practice problems with their worked solutions, the long-form guides, the tool-page copy, the three printable posters, the nine practice datasets, and the capybara artwork. |
| Code | MIT | The shared scripts, the stylesheet, the service worker, each lesson's inline visualization script, and the checking tools that keep the numbers honest. |
Where the two meet, take whichever license suits your purpose.
What you may do
Anything, for any purpose, commercial or not. Some things people have asked about, all of which are permitted:
- Assign lessons in a course at any institution, or embed an interactive in your own virtual learning environment.
- Print the posters, the formula sheet or a whole lesson and hand them out.
- Translate a course into another language and publish the translation.
- Lift a practice problem into an exam, or a dataset into a lab.
- Fork the whole site, strip out what you do not teach, add what you do, and run it for your own students under your own name.
There is no institutional license to sign, no seat count, no time limit and no invoice.
What you must do
Credit the source, and be clear about whether you changed it. Copy this line and adjust it:
Adapted from StatsCapybara by Hakan Karsilar, licensed under CC BY 4.0. Changes were made.
If you reproduced something unchanged, write "From" instead of "Adapted from" and drop the last sentence. For code, keep the MIT copyright notice with it, which is the whole of what MIT asks.
One thing the license does not allow: adding legal or technical restrictions that stop the next person doing what you were just allowed to do. Openness travels with the material.
Two edges worth naming
Eight of the nine practice datasets are simulated by a committed script from a fixed seed, so they belong to this site and travel with it. The ninth is real published data, reproduced as it stands; facts cannot be copyrighted, but the credit for that one belongs to its source rather than here.
The capybara is CC BY 4.0 like everything else, so you may redraw it, recolor it and put it in your slides. What no license grants is permission to pass your version off as this site, or to suggest that it endorses your work. That boundary is a trade-mark matter and sits outside Creative Commons by design.
Citing it
If the site helped a thesis, a paper or a syllabus, a citation is welcome and never required. The repository carries a CITATION.cff file, so a formatted citation is available from the code host, and this works as plain APA:
Karsilar, H. (2026). StatsCapybara: a free, interactive statistics course for visual learners [Open educational resource]. https://statscapybara.com/
Why bother licensing something already free
Free of charge and free to reuse are different promises, and only the second one survives contact with a lecturer who wants to translate a lesson into Dutch or fold a poster into their own handout. Without an explicit license, ordinary copyright applies by default and every one of those uses needs permission first. Most people will not write the email. They will just close the tab, and the material fails at exactly the moment it was becoming useful.
An open license is also the only honest form of the claim this site makes about statistics teaching. Reproducibility, transparent methods and shared materials are what the courses here argue for in Methods and in Ethics. Teaching that while reserving all rights over the teaching would be a strange thing to do.
Corrections and contributions
Corrections are the contribution that matters most, particularly statistical ones. The Spotted a mistake? Tell me link at the foot of every page opens an email with the page address already filled in, and no account of any kind is needed to use it. If you would rather work in the open, the repository takes issues and pull requests.
One rule governs everything here and applies to contributions too: every number is verified against a published source before it ships, and a suite of statistical assertions guards the routines that produce them. If you propose a change that touches a number, say how you checked it.
Questions
If you want to do something and cannot tell whether the license covers it, ask rather than guess. The answer is almost certainly yes, and I would like to hear what you are building. The footer link reaches me.
Licenses applied September 2026. Full terms: CC BY 4.0 legal code · MIT license. See also Privacy and the instructor page.