Edith Cohen Nick G. Duffield Carsten Lund Mikkel Thorup Confident estimation for multistage measurement sampling and aggregation. 109-120 2008 SIGMETRICS http://doi.acm.org/10.1145/1375457.1375471 conf/sigmetrics/2008 db/conf/sigmetrics/sigmetrics2008.html#CohenDLT08