st: Estimating a fractional logit with fixed effects in a non-stationary panel context

[Jonathan Argent <jonathan.argent@gmail.com>]

I would like to estimate the impact of market structure on technology
diffusion in the telecoms industry using a quarterly panel (56
quarters) of all countries (over 200).  I believe that the most
appropriate model for this is a fractional logit with fixed effects
(using the glogit command, or gls, family(binomial) link(logit), with
dummies for different market structure on the right hand side (and
using the margins command to interpret).

Papke and Wooldridge (2008) suggest that in the context of obvserving
the whole population (as I do) the fractional logit with firm specific
intercepts allows unobserved heterogeneity to enter in a flexible way,
but also acknowledges that the fixed effects estimates may be
inconsistent with small T.

1) Are 56 quarters enough that the fixed effects estimation will be consistent?
2) Obviously my data are non-stationary - but I understand that in a
panel context, this is often ok. Would this present a problem for my
standard errors? And if so, how might I correct them?
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