PyQRS is a tool for calculating probabilities and quantiles associated with a large number of probability distributions. In addition, random samples can be drawn. Quantiles and probabilities are displayed and edited in their natural position relative to the probability (density) graph. This makes PyQRS very easy to use.

PyQRS 4.1

PyQRS 4.1 (June 18, 2017) has an improved user interface over its predecessor PyQRS 4.0. It runs on Android (mobile) devices.

Installation is straightforward:

  1. Download PyQRS-4.1.apk (11 MB
  2. After downloading: click/tap on its name; you will be asked whether you want to install the package
  3. Confirm; the app doesn't need access to personal data or peripherals. In order to show wikipedia pages and this web page, you will need a working internet connect

That's all.

A users's manual is available.

Screenshots: standard normal distribution

Screenshots: binomail distribution

PyQRS 4.1

PyQRS 4.1 (June 2017) has an improved user interface over its predecessor PyQRS 4.0. It runs on Android (mobile) devices.

PyQRS 4.0

PyQRS 4.0 (March 2016) is functionally equivalent to its predecessor PyQRS 3. It runs on Android (mobile) devices.

Screenshot of  PyQRS 4.0 Screenshot of PyQRS 4.0
Screenshot of PQRS 4.0

The app is written in Python using the Kivy framework. We could not use Scipy as we did for PyQRS 3. The probability (density) functions and the cumulative distribution functions were therefore programmed in Python. The code could easily be adapted from the Delphi code for PQRS 2.


In 2013 PQRS (was rewritten in Python. In order to distinguish it from the previous PQRS version, and as a tribute to Python and its author, Guido van Rossem, the first letter in its name was replaced by 'Py'.


PyQRS should run under Linux, Windows and MacOS if the following packages are installe

  • python2.7 (already included in many Linux distributions),
  • python-pyside (for the graphical user interface),
  • python-scipy (for the numerical computations)
  • matplotlib (for the graphics).


  • numpy,
  • dateutil,
  • pytz
  • pyparsing,
  • six.

Then download and unpack the compressed file (22 kB) in a directory and in the same directory run:

python2.7 PyQRS.pyc
python2 PyQRS.pyc
python PyQRS.pyc
depending on how python is known to your system.

screenshot of PyQRS 3
Screenshot of PQRS 3

A users's manual is available.


Around the year 2000 PQRS (Probabilities, Quantiles and Random Samples) was designed as a tool for students using computer aided instruction of statistics in order to make printed tables obsolete. PQRS was written in Delphi and runs under Windows and - with the help of Wine - under Linux.


Download the compressed file (0.7 MB), unzip it and start PQRS.exe.

Screenshot of PQRS 2
Screenshot of PQRS 2


Our first program (mid 1990's) replacing tables of probability distributions, running under MS-DOS. It was written in Pascal by Sytse Knypstra and Arjen Merckens


You can contact the author, Sytse Knypstra, at his e-mailaddress:
Sytse.Knypstra (at)