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Special seminar "Advanced statistics for discoveries"

April 12, 2012 - Introduction
April 24-25, 2012 - Advanced theory and hands-on part
IIHE ULB-VUB, Large seminar room
How to get to the IIHE: click here

Organised by Pascal Vanlaer (ULB) and Jorgen D'Hondt (VUB)

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This special 3-day seminar on "advanced statistics for discoveries" provides the advanced statistical foundations that allow discrepancies with an expected background to be quantified, paving the way to a discovery. It is meant for graduate students and above. It covers tests of the presence of a new signal and the evaluation of its significance, both in theory and in practice using the RooStats statistical tool.

The seminar is organised as follows: on the first day, a reminder of statistics will be given by IIHE staff (fitting and hypothesis testing); followed by a simple RooStats exercise in the afternoon, taught by IIHE PhD students. The second part would be taught by Wouter Verkerke, one of the RooStats authors, from NIKHEF, who will teach the advanced theory part interleaved with hands-on exercises.

People attending must come with a laptop configured as described [#platform below]. The configuration contains a virtual machine with the required operating system and Root version already installed, that guarantees a unique platform for all people attending. This setup is mandatory. In case of problems, please contact grid_adminATlistserv.ulb.ac.be

This seminar is organized with financial support from the doctoral schools on Physics and Astrophysics (Ecole doctorale thematique PandA - Communaute francaise de Belgique) and on Natural Sciences and (Bioscience) Engineering (NSE - VUB), the Fonds de la Recherche Scientifique (F.R.S.-FNRS) and the Fonds Wetenschappelijk Onderzoek (FWO).

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Seminar programme

Advanced theory and hands-on part


Maximum 35 people at a time can attend the seminar. Register by entering your name into the doodle poll

The dates of the seminar have been fixed, but there are still a few places left. People who can't attend the introduction day can participate to the advanced theory and hands-on part on April 24-25 provided that they feel confortable with parameter estimation and hypothesis testing, and master the RooStats tutorial taught in the introduction (see the Introduction link from the Seminar programme above). In this case please register your name in the poll above, leaving all days red.


Installation of a Virtual machine for the statistics course

Please follow the instructions to install the virtual machine containing the root version necessary to follow the statistics course. It is a mandatory installation, so that everybody starts with the same settings.
Most of the instructions work for Linux, MAC and Windows. There is an extra section specially for windows users, as they require some more installation. there is also a special procedure for Ubuntu users as the standard VM does not work on this distribution.

Install Virtual Box

Virtual Box is the software that will allow you to run a 'guest operating system' that is different form the one you use now.
Go to https://www.virtualbox.org/wiki/Downloads and download the version of Virtual Box for the operating system that is installed on you laptop now and install it.

Prepare the ground

To be able to run the virtual machine (VM), we need to configure virtualbox.

From the virtualbox download page, download the extension pack.
Open VirtualBox; go to the following menus: File > Preferences > Extensions.
Click on the triangle to add a package
Browse to where you saved the extension file and add it.

Next, in the same window, click on Network. And add a Host-only network.
The new network should also have the name vboxnet0

Install the VM

Ubuntu users need to follow the second procedure. Other users are recommended to use the first procedure, although the second might also work for them. This was, however, not tested.

For all platforms except Ubuntu

Download the file with the VM: http://mon.iihe.ac.be/~odevroed/VM/VirtualBox_Fedora.tar.bz2
also available here :
bunzip and untar the file.

Then, in VirtualBox, click: Machine > Add ; Go to the directory where you untarred the file and select "Fedora16.vbox".
A new Icon with the VM will come up. Just start the new VM and you have a working Fedora 16 with lightweight xFCE window manager.

For Ubuntu users

Download the file with the VM: http://mon.iihe.ac.be/~odevroed/VM/Ubuntu.ova
Also available here :
Then, in VirtualBox, click: File > Import Appliance > Choose
Then browse to the downloaded file and import it.

run Root

We could run root from the VM window, but as this is a bit small, we will just run it from a terminal on our laptop.
Log into the VM as user course (password= course;123 the same password holds for root)
Open a terminal (black icon in lower left ) and type: ifconfig
look for the line "inet addr:" ; The last digit (3) will probably be different on your system. It is this IP address that we will ssh to.

ssh -X course@192.168.56.X

And then run root. The root icon should now appear in your laptop. Test the settings by opening a TBrowser for instance.


To test if all RooStats libraries required are correctly installed, try:

  cd $ROOTSYS/tutorials/roostats
  root -l StandardHypoTestInvDemo.C

This will run the full chain of building a model, storing it in a workspace, reading it in and calculating a CLS limit use a PLL test statistics. It takes about 90 seconds to execute.

Extra instructions for Windows users

On windows you might need another step, as the VM host only network does not have the same name. To do this, right click on the name of VM > configuration > network
In the second tab (named card 2), change the name to whatever card name you can find in the drop-down menu.
As the VM contains linux, it natively runs X-windows. This is unfortunately not the case for windows. You need to install an X server. This one works: http://sourceforge.net/projects/xming/?_test=b , but you might already use another one.
Then, install an ssh client. The most famous is putty: http://the.earth.li/~sgtatham/putty/latest/x86/putty.exe
Determine the IP of the VM as above and ssh to the machine, before go to the options on X11 and put X11-forwarding on.