AGREEMENT

This Software was developed by the Research Group of Quantitative 
Psychology and Individual Differences and is owned by the Katholieke 
Universiteit Leuven, for the purpose of this Agreement represented by 
the Research Group of Quantitative Psychology and Individual 
Differences and hereinafter referred to as KULEUVEN. By downloading 
and or installing the Software and associated files on your computing 
system you agree to use the Software under the terms and condition as 
specified in this Agreement.

Article 1 - Definitions
1.1	"Software" shall mean KULEUVENs software described in Annex A 
      including the source code.
1.2	"Additions" shall mean lines of code, which are added to the 
      Software and which optimize an existing functionality of the 
      Software.
1.3	"Module" shall mean lines of code, which add a new functionality 
      to the Software regardless of the fact that this new function is
      operative without the Software.
1.4	"Effective Date" shall mean the date on which you download or 
      install the Software and associated files on your system.

Article 2 - License
2.1	You shall have a non-exclusive, non-transferrable license to the 
      Software supplied by KULEUVEN for Academic Purposes. All other 
      uses are prohibited, except to the extent provided in any 
      separate agreement. You acknowledge and agree that you may not 
      use the Software for commercial purpose without first obtaining 
      a commercial license from K.U.LEUVEN.
2.2	For the purposes of this Agreement "use for commercial purposes" 
      shall include the use or transfer of the Software for a 
      consideration as well as the use of the Software to support 
      commercial activities.
2.3	Any use of Software for commercial purposes without first 
      obtaining a license from KULEUVEN shall be deemed a breach of 
      this Agreement for which KULEUVEN shall be entitled to whatever 
      remedies it may have under law or equity, including recovery of 
      consequential damages.
2.4	You shall not sublicense any of your rights to the Software. 
      Neither will you transfer the Software to a third party, unless 
      prior written agreement of KULEUVEN has been obtained. 
2.5	KULEUVEN retains the right to the Software. Nothing in this 
      Agreement shall preclude KULEUVEN from entering into agreements 
      with third parties concerning the Software.

Article 3 - Ownership
3.1	The Software is copyrighted and KULEUVEN retains all title and 
      ownership to the Software.
3.2	In case you introduce an Addition to the Software, the KULEUVEN 
      will be informed immediately of the existence and nature of such 
      Addition. Additions will become the property of KULEUVEN.
3.3	Any Modules you create shall remain your property. Nevertheless, 
      you will inform KULEUVEN on the existence and nature of any 
      Module created under this Agreement. Moreover, you will, upon 
      request of KULEUVEN, make available the Modules to KULEUVEN for 
      use for Academic Purposes.

Article 4 - Confidentiality/Publication
4.1	Each of the Parties agrees to keep strictly confidential any 
      information, technical as well as commercial, obtained from 
      another Party under this Agreement and not to communicate such 
      information to third parties.  This obligation of 
      confidentiality is not applicable to information:
	of which the receiving party was already in the possession at 
      the time the information was acquired from the disclosing party;
	which was, at the time the information was acquired by the  
      receiving party, already common knowledge;
	which became common knowledge after it was received from the 
      disclosing party and without any fault of the receiving party;
	which the receiving party acquired from a third party who was in
      good faith and in possession of the information and allowed to 
      disseminate the information without confidentiality obligations;
	of which the receiving party can prove that the information was 
      developed by the receiving party independently from the knowledge 
      and skills or experiences received from the disclosing party.
4.2	The Parties have at all times the right to publish articles 
      regarding the Software and regarding output as obtained from the 
      Software, provided that the above obligation of confidentiality 
      is respected. In all such articles, however, an explicit
      reference citation to all papers as listed in Annex A has to be 
      included.

Article 5 - Financial Arrangements
5.1	The Software will be provided at no cost.

Article 6 - Third party rights
6.1	You will indemnify and hold harmless KULEUVEN against any 
      damages, costs (including attorneys fees and costs) or other 
      liability arising from claims that your use of the Software as 
      provided under this Agreement, infringe any patent, copyright, 
      trade secret, or intellectual property right of any third party. 
      However, in no event you will have the obligation to indemnify 
      and hold harmless KULEUVEN against any damages, costs or other 
      liability arising from claims solely based on agreements between 
      KULEUVEN and third parties.

Article 7 - Warranty
7.1	The Software is provided "as is" by KULEUVEN without warranty of
      any kind, whether express or implied.  KULEUVEN specifically 
      disclaims the implied warranties of merchantability and fitness
      for a particular purpose.
7.2	KULEUVEN shall not be responsible for any loss, direct or 
      indirect damage or other liability incurred by you or any third
      party in connection with the Software licensed by KULEUVEN under
      this Agreement. Under no circumstances shall KULEUVEN be liable
      for any direct, indirect, special, incidental, or consequential
      damages arising out of any performance of this Agreement, 
      whether such damages are based on contract, tort or any other
      legal theory. You shall defend, indemnify and hold harmless 
      KULEUVEN from all losses, damages, expenses, costs and other
      liabilities in connection with your use or disclosure of the
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Article 8 - Term
8.1	This Agreement is effective from the Effective Date until you 
      delete the Software and any and all related files from your 
      computing system.
8.2	In case of termination the provisions of Article 3, 4, and 7
      shall remain in full force and effect.

Article 9 - Miscellaneous
9.1	Any notice authorised or required to be given to KULEUVEN under
      this Agreement shall be in writing and shall be deemed to be
      duly given if left at or sent by registered post or facsimile
      transmission addressed to:

	Research Group of Quantitative Psychology and Individual
      Differences

      Address:	Tiensestraat 102
			B-3000 Leuven
			Belgium
			Fax:	016 32 59 93
	Attention:	Head of the Research Group

9.2	You shall not assign this Agreement wholly or partially to any
      third party without the prior written consent of the other two
      parties.
9.3	Any modifications or supplements to this Agreement shall be in
      writing and duly signed by the Parties hereto to become legally 
      binding.
9.4	The terms and conditions herein contained constitute the entire 
      agreement between the Parties and supersede all previous 
      agreements and understandings, whether oral or written, between 
      the parties hereto with respect to the subject matter hereof.

Article 10 - Conflicts
10.1	In the event of conflicts in the interpretation and/or 
      performance of this Agreement, the parties shall first undertake
      to settle their differences amicably. If no amicable settlement
      can be reached concerning the execution and/or interpretation of 
      this Agreement, such conflict shall be brought before the courts
      of Leuven and Belgian Law shall be applicable.


Annex A: Description of the Software 

difR is an R-package that allows to detect differential item 
functioning (DIF) among dichotomously scored items. It contains 
several classical methods to identify uniform or nonuniform DIF 
between two or more groups of examinees, using either a parametric 
(IRT) or a nonparametric (non-IRT) approach. 

Authors
difR was created by David Magis, Francis Tuerlinckx and Paul De Boeck 
of the Research Group of Quantitative Psychology and Individual 
Differences of the K.U. Leuven, and by Sebastien Beland of the 
Universite du Quebec a Montreal (UQAM). The final package was compiled 
with the help of Gilles Raiche of UQAM.

References
Magis, D., Beland, S., Tuerlinckx, F. and De Boeck, P. (2010). A 
general framework and an R package for the detection of dichotomous 
differential item functioning. Behavior Research Methods, 42, 847-862.