Provides utility classes to manage statistics in the blend/multi-skill call center simulator. The system for managing statistics is split into two parts: counters updated throughout the simulation, and collectors updated only at the end of steps using the values of counters. Counters and collectors are regrouped into matrices whose rows correspond to call types, agent groups, or (call type, agent group) pairs, and columns represent time intervals. We now examine how counters and collectors are managed and interact in more details. The abstract class {@link umontreal.iro.lecuyer.contactcenters.msk.stat.CallCenterMeasureManager} represents the matrices of counters. It can be used to list the supported types of measures, and return matrices of values for any supported type. Getting a matrix of values is done by reading the corresponding counters, and performing some computations such as regrouping periods or normalizing with respect to time. The exact computation depends on application and thus on the concrete subclass. Usually, the matrices of counters contain one column per period, and matrices of statistical collectors have one column per main period, plus an extra column representing the whole horizon. The measure manager also encapsulates some observers linked to the call center model in order to collect the appropriate statistics. These observers use an instance of {@link umontreal.iro.lecuyer.contactcenters.msk.stat.StatPeriod} to obtain the statistical period of any processed call. The call center measure manager also includes an instance of {@link umontreal.iro.lecuyer.contactcenters.msk.stat.CallByCallMeasureManager}, which regroups every counter containing sums with one (possibly 0) term for each simulated call. On the other hand, the interface {@link umontreal.iro.lecuyer.contactcenters.msk.stat.CallCenterStatProbes} represents a set of matrices of statistical collectors. The most common implementation of this interface is {@link umontreal.iro.lecuyer.contactcenters.msk.stat.SimCallCenterStat} which provides a method \texttt{addObs} to add matrices of counters, obtained using an instance of {@link umontreal.iro.lecuyer.contactcenters.msk.stat.CallCenterMeasureManager}, to the corresponding matrices of collectors. Other implementations of the interface can be used to collect statistics about statistics, e.g., averages of averages, variances, etc., combine the information given by two instances of {@link umontreal.iro.lecuyer.contactcenters.msk.stat.SimCallCenterStat}, etc. This can be used to apply some variance reduction techniques such as stratification and randomized quasi-Monte Carlo methods.