What is the order of autocorrelation?

[Pete Willemsen]

I have the following equation:

lpowt=β1+β2lprot+β3t+β4t2+ut
Where:
lpow=natural logarithm for mining power use
lpro=natural logarithm for mining production
t= time (in quarters)

How do I determine what the order of autocorrelation is

[Phil Bromiley]

The time series manual probably talks about this. https://www.stata.com/meeting/new-or...ola13-baum.pdf and http://www.columbia.edu/~so33/SusDev/Lecture_8.pdf are also relevant.