Hey Deb, NDCG is the "Normalized Discounted Cumulative Gain" [1]. Another popular measure is "Expected Reciprocal Rank" (ERR) [2]; it is based on a probabilistic user model, where the user scans the presented list of search results or recommendations and chooses the first that is sufficiently relevant. ERR is the expectation of the reciprocal rank under this model. Precision@k is the precision at a cut-off k. Often this is used as an overage over the first n k's; a starting point might by [3].
Hope that helps. Cheers, Christoph [1] K. Järvelin and J. Kekäläinen. Cumulated gain-based evaluation of IR techniques. ACM Transactions on Information Systems, 20(4):422–446, 2002. [2] O. Chapelle, D. Metzler, Y. Zhang, and P. Grinspan. Expected reciprocal rank for graded rel- evance. In Proceeding of the Conference on Information and Knowledge Management, 2009. [3] http://en.wikipedia.org/wiki/IR_evaluation
