Information Retrieval Exercise VII.3 Q5

Information Retrieval Exercise VII.3 Q5

by Jin Yang Peh -
Number of replies: 2

Hello,

I would like to ask how would I go about drawing the Precision/Recall curve for each system for each query. How does the Precision-Recall curve looks like for this question?

 I plotted points of Precision@rank_k and its corresponding recall for each of the query but I am not sure how to extend it from recall of 0 to recall of 1. From my understanding, the Precision-Recall curves are drawn from recall = 0 to recall = 1. Given that I have only a few coordinates of (Precision,Recall) for each query, how would I interpolate the line from a recall of 0 to a recall of 1?

Thank you.

In reply to Jin Yang Peh

Re: Information Retrieval Exercise VII.3 Q5

by Jean-Cédric Chappelier -
The way **that** question is formulated does not lead to *curves* but only to 8 points : the 8 (R,P) points from subquestion (3). That's what the sentence "As it would be too tedious [...]" means: don't draw a curve, simply put those points.
Now in real life there is more computation done (e.g. averaging, or taking the max, etc.) but the principle remains the same: the precision is plotted against the recall: the recall is simulated by asking the system to retreive more and more documents up to a point when all documents have been retreived (R=1 then).
For R=0, since this does not have any mathematical sense (but only that P=0 as well), then this point is generally used to display another information, very often the max (best possible P reached by the system).