1 • VARIABLES Total.WaitCost—Total waiting cost. This is the total wait cost for all entities. Total.TranCost—Total transfer cost. This is the total transfer cost for all entities. Total.OtherCost—Total other cost. This is the total other cost for all entities. Total.EntityCost—Total entity cost. This is the sum of the costs in the five allocation categories above for all entities. This can be a simple way of determining the total cost of all entities. Note that this number will typically include those resource costs that can be attributed to a specific entity. Total.ResUseCost—Total resource usage cost. This is the total of the usage costs (for example, costs per seize) for all resources. It is the product of ResSeizes( ) * ResUseCost( ), summed for all resources. Note that these costs are typically also included in entity costs because they can be assigned to a particular entity. Total.ResBusyCost—Total resource busy cost. This is the total of the busy costs (for example, costs while seized) for all resources. It is the product of ResBusyCost( ) * Average Number Busy * TNOW, summed for all resources. Note that these costs are typically included in entity costs as well because they can be assigned to a particular entity. Total.ResIdleCost—Total resource idle cost. This is the total of the idle costs (for example, costs while scheduled, but not busy) for all resources. It is the product of ResIdleCost( ) * Average Number Idle * TNOW, summed for all resources. Note that these costs are never included in entity costs because they cannot be assigned to a particular entity. Total.ResourceCost—Total resource cost. This is the sum of the costs in the three categories above for all resources. This can be a simple way of determining the total cost of all resources used in the system. Total.SystemCost—Total system costs. This is the sum of all costs. This can be a simple way of evaluating the total cost of one system relative to another. It is the sum of Total.EntityCost and all costs that have been incurred, but not yet allocated to an entity. Statistics collection variables A set of variables is provided to access information about each type of Arena statistic. The types of variables provided depend upon the statistic type. Most of these variables take the statistic identifier as an argument; frequency variables take the 21

ARENA VARIABLES USER’S GUIDE frequency number and, in some cases, category number. All of these arguments are required. When simulation statistics are cleared between replications or by the Warmup Period, the statistics variables are reinitialized to their default values unless otherwise noted. Unless otherwise stated, these variables are not user-assignable. Counter statistics variables MC ( Counter ID )—Count limit. MC is the limit defined in the Counters (or Statistic) module; if the limit is defaulted, MC is given a value of 0. MC is user-assignable; its value (if changed) is retained between replications. It is not affected by statistics reinitialization. NC ( Counter ID )—Count value. Each time a count occurs, NC is changed by the specified value. The Initialize Statistics option on the Replication Parameters page of the Run > Setup dialog box determines whether counters are initialized between replications. Time-persistent statistics (Cstat) variables CAVG ( Cstat ID )—Average value. CAVG records the average of the cstat expression throughout the replication. CMAX ( Cstat ID )—Maximum value. CMAX records the maximum value taken by the cstat expression during the replication. CMIN ( Cstat ID )—Minimum value. CMIN records the minimum value taken by the cstat expression during the replication. CSTD ( Cstat ID )—Standard deviation. CSTD calculates the standard deviation of the recorded values of the cstat expression. CTPD ( Cstat ID )—Time period. CTPD returns the time period over which the statistics have been collected. If a Warmup Period is provided on the Replication Parameters page of the Run > Setup dialog box, CTPD increases from 0.0 to the warmup time. After the warmup time, it is restarted from 0.0. CHALF ( Cstat ID )—Half-width. CHALF returns the 95% confidence interval around the mean value of the specified cstat. If there is insufficient data, the data is correlated or an error is detected; this will return a very large number. CVALUE ( Cstat ID )—Last recorded value. CVALUE returns the last recorded value for the specified cstat. When animating a cstat histogram, it is CVALUE, not the CAVG, that is typically displayed. 22