-------------- Interaction Association Score (IAS) ------------
-------------- Release Date : 26th January, 2015 ----------------
-------------- File created by : Ishita K Khan, Ph.D Student, Compute Science -----------------

Functional Association Score (FAM) score is computed between 2 GO terms as a contexual association between the terms in annotation database Uniprot.org. Briefly, the method to compute FAM score consists of the following steps -

The GO term Interaction Association Score (GO_IAS) captures the relationship between two GO terms by normalizing the GO term pair co-occurrence count with the number of protein-protein interactions and also with the number of times each of the participating GO terms is used for protein annotation in the interaction data. Once we obtained the #GOterm pair counts and #individual GO term counts as mentioned in 2.2.1, we calculated the GO_IAS for each true positive GO term pair as follows:



 
				 N(GOx-GOy)
				------------
			  	  #T.Edges
GO_IAS(GOx, GOy) = -------------------------------------
			   N(GOx)         N(GOy)
			 ( -------- )  ( -------- ) 
			  #T.Edges        #T.Edges



Where N(GOx-GOy) is the number of times GO term pair GOx and GOy interact in the PPI network, #T.Edges is the total number of true positive protein-protein interactions, N(GOx) and N(GOy) are the number times GOx term and GOy term individually occur in the network and #T.Nodes is the total number of unique proteins considered.

To extract PPI interactions, BIOGRID version 3.2.107 was used. This data is released as the supplemental material for "IAS: Interaction specific GO term associations for predicting Protein-Protein Interaction Networks" by Satwica Yerneni, Ishita K. Khan, Qing Wei, and Daisuke Kihara.