In order to test the performance of the PPV with default parameters (nFit/nPoss = 0.7 and dcaR < 3), I produced a small test sample of 200 events in each of four partonic pT bins for three groups of run ordered by ZDC coincidence rate. These 200 events are not trigger filtered events. The ratios that I looked at are
1) GoodNo: no positive vertex found
2) GoodYesMatchNO: positive vertex found but none of them matches with the vertex thrown
3) GoodYesLowMatchYes: positive vertex found but one of lower but positive ranked vertex matches with the vertex thrown
4) GoodYesHighMatchYes: the highest positive ranked vertex matches with the vertex thrown.

The three groups of runs are

0: (~191k)