  Setcover greedy algorithm is a natural approximation algorithm for test set
problem. This paper gives a precise and tighter analysis of performance
guarantee of this algorithm. The author improves the performance guarantee
$2\ln n$ which derives from set cover problem to $1.1354\ln n$ by applying the
potential function technique. In addition, the author gives a nontrivial lower
bound $1.0004609\ln n$ of performance guarantee of this algorithm. This lower
bound, together with the matching bound of information content heuristic,
confirms the fact information content heuristic is slightly better than
setcover greedy algorithm in worst case.
