Dynamic panel estimation and instrument rank

[sali_boua]

Hi everybody,
can EViews explain me how the instrument rank is calculated.
If I use the ab data, with 7 periods used and just a simple model wher i have no explanatory variables and only one lagged variable the théory says that the number of instruments is 0.5*(T-1)*(T-2) = 15 instruments in that case. Why then EViews is giving an instrument rank équal to 28?
Many thanks

[EViews Glenn]

I'm unable to replicate this result. Can you post your workfile? What is the build-date on your copy of EViews?

I just created a 7 period panel and ran DPD on it with a first difference model and obtained an instrument rank of 15.