Creating Experiments with WE2

This page summarizes the information on the following topics. I also recommmend you read the WebExp2 User Guide, which describes both the XML language used by WE2 (for experimental design and for the results output) and the client-server architecture used by WE2.

• Creating WE2 input files
• Uploading your experiment to the WE2 server

Creating WE2 input files

The new front end, WebExpCreator (by Benjamin Cody, University of Edinburgh) will make creating WE2 experiments a whole lot easier. As of now, the software is still under development, but it already proofs an enourmous help to create WE2 XML input files. It includes an preview function which is also extremely useful (this way you can preview the slides of your experiment). You can create both the stimulus file and the resource files using this tool. Check it out.

I tested the software on a PC and it works without problems (just download the JAVA program following the link given above), but there were some issues for MAC users, which Neal Snider and Benjamin Cody figured out:

Getting WebExpCreator started on Mac OS X (by Neal Snider)
You can get webexpcreator working on your mac! It involves mucking with some system files, but what I am going to have you do also backs up your old configuration in case there are problems (just ask me for help restoring). Anyway, here's how:

Open terminal and type:

cd /System/Library/Frameworks/JavaVM.framework/Versions
sudo mv Current Current.old

type in your password, then run:

sudo ln -s 1.5 Current
sudo mv CurrentJDK CurrentJDK.old
sudo ln -s 1.5 CurrentJDK

then go to your WebExpCreator directory and type:

./run.sh

It should work!

Uploading your experiment to the WE2 server

After you finished designing and testing your experiment (and crucially, well before you advertise it ;-), you have to upload your experiment to the WE2 server.

The WE2 server reads in new experiments at 1:15am every night. In order for your experiment to be read in the following conditions have to be fulfilled:

Register your experiment in your experiments.xml file in ~YOUR-SUNET-ID/WE2data/. For that open experiments.xml

emacs -nw ~YOUR-SUNET-ID/WE2data/experiments.xml

and add the following lines at the end of the file (but before the closing </config> tag):

<id>EXPERIMENT-ID</id>
<name>EXPERIMENT-NAME</name>
<max-subjects>NUMBER-OF-SUBJECTS</max-subjects>
.

where EXPERIMENT-ID must be a unique identifier (i.e. no other <experiment> tag in the experiments.xml file can contain the same ID. The second tag can be used to specify a longer name for your experiment (EXPERIMENT-NAME). Be aware that this name shows up as the title of the browser window that subjects will see. So choose a name that does not give away what your experiment is about. The same holds for the EXPERIMENT-ID. Finally the <max-subjects> tag is entirely optional (you can leave it out). If specified, the server will not direct further subjects to your experiment once the specified number of participants has been reached (only complete experiments will be counted).

All experimental data and resource files must be located in the directory ~YOUR-SUNET-ID/WE2data/EXPERIMENT-ID/.

The file name of the file containing the experimental design must be EXPERIMENT-ID.xml and, of course, it must confirm to the XML specifications given in the WebExp2 User Guide (Chapter 5).

The directory ~YOUR-SUNET-ID/WE2data/EXPERIMENT-ID/ and all of its subdirectories must be readable and writable for the we2 group.

chgrp -R we2 ~/WE2data/
chmod -R g+rwx ~/WE2data/

Note that, if you're using the local WE2 server on symsys.stanford.edu, up to 24 hours may pass before your experiment will show up (or update, in case you had uploaded an earlier version). This is because - in its current version - the WE2 server only reads in experiments whenever it is reset. This is done by means of a cronjob (a process running on symsys.stanford.edu) that resets the WE2 server each night at 1:15am. If it is absolutely urgent for your to reset the server, contact the person who is running the server (currently Florian).