.. _qa_charts:

Plotting your data
==================

There are currently two ways of plotting your data 1) basic time series
plots and 2) statistical process control charts (SPC) (see `Statistical
process control for radiotherapy quality
assurance <https://aapm.onlinelibrary.wiley.com/doi/abs/10.1118/1.2001209>`__).

.. Note:: Anywhere you see a little chart icon ( |quick chart| ) next to a
    test you can click on it to automatically be taken to a chart of that
    data

To access the chart interface choose the **Charts** menu item from the
**Review Data** dropdown menu at the top of any page.

.. figure:: images/charts_menu.png
   :alt: Charts option of the Trends and Analysis menu

   Charts option of the Trends and Analysis menu


The basic functionality of the charts page should be fairly self explanatory.
First select the units you are interested in, and then select the test
lists/tests you would like to plot data for.

.. figure:: images/tests_to_plot.png
   :alt: Choose tests to plot

   Choose tests to plot

There are a number of chart options which you can change:

- **Combine test data for unit**: Combine results for the same test from
  different test lists into a single series

- **Plot relative to reference values** If selected, the absolute difference is
  plotted for tests with absolute tolerances set or with reference values of
  zero, otherwise the percent difference is plotted.

- **Show Service Events** If checked, then charts will show markers along the
  x-axis for Service Events that occured on a Unit.

- **Service Types** Select the types of Service Events you want to show on the
  chart.

To create an SPC choose the **Control Chart** option from the **Chart Options -
Type:** dropdown.

Once you are happy with the options, click the **Generate Chart**
button.

.. figure:: images/time_series.png
   :alt: Time Series Plot

   Time Series Plot


.. figure:: images/time_series_se.png
   :alt: Time Series Plot showing a Service Event marker

   Time Series Plot showing a Service Event marker

The foo time series plots are interactive and you can pan/zoom the data
using the sliders at the bottom of the chart.

In order to save a time series chart to an image, click the `Save Chart` button
and a PNG image of the graph will be created.

.. figure:: images/save_chart.png
   :alt: Save Chart

   Save Chart

You can also use the URL located in the link text box under the chart to share the chart
with other users.

.. figure:: images/control_chart.png
   :alt: Control Chart

   Control Chart

To save a control chart, right click and select *Save Image As*.

Notes on Control Charts
~~~~~~~~~~~~~~~~~~~~~~~~

.. note::

    For details on the terminology & definitions of control charts please see
    the paper by Pawlicki et al (2005):
    https://aapm.onlinelibrary.wiley.com/doi/abs/10.1118/1.2001209

To specify where your baseline data comes from you can use the **Date
Filters** under the **Generate Chart** button. For example if there was
a reference change on 5 Nov 2012 then you would set the **From:** date
filter to 5 Nov 2012 and the baseline points will be taken starting on
that date.

.. |quick chart| image:: images/quick_chart.png