Downloads

This section contains resources produced by Capacitas as part of our programme to support and promote performance and capacity management across the ICT industry.

Capacitas Excel Add-In

Capacitas has developed a free Microsoft Excel Add-In to support analytical modelling of ICT systems using Excel worksheet functions.

The Capacitas Excel Add-In works under both Excel 2003 and 2007 and contains the following six worksheet functions:

• An Erlang C function to estimate the probability that all of a number of servers are busy at a given average load per server
• A function to estimate response times (either with or without service time) for a system that may be approximated by an M/M/N queuing model
• A function to estimate response times (either with or without service time) for a system that may be approximated by an M/G/1 queuing model
• A function to estimate response times (either with or without service time) for a system that may be approximated by an M/G/N queuing model
• An Erlang B function to estimate the probability of call dropping based on a number of lines and the load
• A function that uses the Erlang B function to predict the number of lines required to achieve a particular grade of service based on an assumed load

The use of these functions and the principles behind analytical modelling are described in detail in the Capacity and Performance Management: Tools and Methods training course.

Contents

capacitas.zip contains the following files

• CAPACITAS.xla - the Excel Add-In
• Capacitas Queuing Examples.xls - an Excel spreadsheet that describes the use of each function, along with an example
• licence.txt - the licence agreement

Installation Instructions

Follow these steps to download and install the Capacitas Excel Add-In:

• Click on capacitas.zip to download the Add-In
• Unzip and save CAPACITAS.xla into the appropriate Add-Ins directory (for example, C:\Program Files\Microsoft Office\Office\Library or C:\Documents and Settings\UserName\Application Data\Microsoft\AddIns)
• Start Microsoft Excel
• If you are using Excel 2003 then select 'Add-Ins...' from the 'Tools' menu

  

• If you are using Excel 2007 then click the Office Button in the top left hand corner and select 'Excel Options' from the menu

  

• Then highlight 'Add-Ins' on the left hand menu and click 'Go..." at the bottom of the screen next to 'Manage: Excel Add-ins'

  

• The remainder of the process is the same for both Excel 2003 and 2007

• Click the 'Browse...' button, manually locate CAPACITAS.xla and click 'OK'

  

• Check the 'Capacitas Functions' checkbox and click 'Ok'

  

• You are now ready to begin using the Capacitas queuing functions
• Open the 'Capacitas Queuing Examples.xls' workbook to see examples of the queuing functions in use

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