Calculating Confidence Intervals in Bottleneck Charts

A bottleneck is a phenomenon where the performance or capacity of an entire system is limited by a single sub-system component or a set of sub-system components. Confidence interval (CI) appears in the bar chart of the average bottleneck times. You can define the confidence level in the dialog box, which has three options, 90, 95 and 99.

  1. Select the Detect Bottleneck check box from simulation options tab.

    For more information, see Detecting Bottlenecks

  2. Run the simulation (for example you can set: 100 seconds with 0 warm up time).
    Note: Working period is time, when a system continuously works till it is interrupted (blocked or starved). Number of working period is the count of working period over a length of simulation. Confidence Interval cannot be calculated if there is only one working period.
  3. Select the Global Chart dialog box and open the Bottleneck tab.
    You can view the bottleneck values at the end of simulation.

    Note: If two systems CI overlap, then we cannot make out as which system is in bottleneck, you have to collect samples by running the simulation for extra time. If the CI does not overlap, then we can make out that the system is in bottleneck.

  4. Select the bottleneck time bar in the graph to highlight the system tile in the authoring window.