Overlapping Experiments

A computer-implemented method for performing overlapping experiments, comprising:

• receiving a plurality of user queries, each query requesting a service from a server;
• and
• performing, on at least one digital computer, overlapping experiments on at least a portion of the queries, each experiment modifying zero or more parameters associated with the queries or parameters associated with processing of the queries, in which the experiments are organized in a plurality of layers;
• wherein two or more experiments in different layers are allowed to be performed on a same query, and for any given layer, at most one experiment is allowed to be performed on the same query.