# Metrics

## In the "service_in_time_counters" table, how is the value for "num_calls_answered" determined?

If the call is distributed to an agent, and that agent answers either manually or via auto answer, that call would count toward the *num_calls_answered* metric. For more information on this metric and others in the *service_in_time_counters* table, see the Reporting Database Specification.

## How is EWT Calculated?

Imagine there is a service queue with incoming interactions and a pool of agents assigned to this service.

To calculate Estimated Wait Time (EWT), we use a probabilistic approach. That is, the conditional probability of an event occurring within a given time interval is calculated with the assumption that agents become Ready over time, according to the exponential distribution.

So, if an interaction comes into the service queue and there is an agent in the *Ready* state, then EWT is 0. If all agents are in a Busy state at this moment, we can calculate the probability of the event when an agent becomes available within a certain amount of time.

The probability distribution, in this case, can be approximately described as an exponential distribution where the parameter of distribution is proportional to the total number of agents and inversely proportional to the sum of Average Handle Time and Average After Call Work (ACW) Time.

If we select a confidential interval, then we can calculate a distribution of probability for agents to become available. Resolving the equation after a number of transformations, we can find a value for probable wait time. This is proportional to the queue length and inversely proportional to some probable *handling time* with *current handling time* uniformly distributed among available agents and the probable number of interactions, which sit in the queue ahead of current interactions and will be abandoned based and calculated on the value of average abandon time.

## What is the definition of "total_busy_time_in"? What about "total_busy_time_out" and "total_ready_time"?

These metrics and others are defined in the *Reporting Database Specification*. Those specific metrics are defined in section agent_performance:

**total_busy_time_in**- Specifies the sum of times the agent was busy with inbound calls; includes hold times, but does not include ringing time or after call work time**total_busy_time_out**- Specifies the sum of times the agent was busy with outbound calls; includes hold times, but does not include dialing time or after call work time**total_ready_time**- Total time the agent spent in the Ready state during the aggregation interval< Previous | Next >