The number of lags for the parametric spectral analysis needs to be chosen. A recent paper that examined similar frequency ranges used 32 lags:
Babapoor-Farrokhran, S., Vinck, M., Womelsdorf, T., and Everling, S. (2017). Theta and beta synchrony coordinate frontal eye fields and anterior cingulate cortex during sensorimotor mapping. Nature Communications 13967.
I haven't thought about this a lot, but that's a least a starting point.
The number of lags for the parametric spectral analysis needs to be chosen. A recent paper that examined similar frequency ranges used 32 lags:
I haven't thought about this a lot, but that's a least a starting point.