Wireshark-users: [Wireshark-users] How to calculate mean jitter values

From: "Ravi Inder Singh" <raviinder@xxxxxxxxx>
Date: Sun, 15 Jun 2008 22:19:44 +0530
Hi all,
  Thanks all,
    i got help from link bleow i.e how to find jitter values ,

    http://www.mail-archive.com/wireshark-users@xxxxxxxxxxxxx/msg01653.html

But now i want to calculate Mean Jitter values ? As there given in above link there is a file aaa.cap, Means values comes out to be 18.09 how ??
PLease anyone can explain in detail how to calculate it.

Thanks in advance
Ravi Inder Singh