[ntp:questions] ntp behaviour at startup

[marknmbox-88 at yahoo.com]

I see a single line and a single chart in NTP FAQs
that discusses how long after startup 
until NTP reaches a good and stable value.

That line is 

"Also keep in mind that corrections are applied
gradually, so it may take up to three 
hours until the frequency error is compensated"

Can anyone point me to additional information or
additional studies on how this subject?

                                                      
                            Mark