CES VŠEM o aktuálních ekonomických problémech

is medium) while the number of periods
sample. 66
3.3 Robustness tests
is large in our
As our previous sets of results may be influenced by the
composition of our group of NMS states, including countries of
different levels of economic development, we will check for
robustness of our results with the help of four sets of
specifications. First, we will try to assess effects of group
composition. Second, we distinguish between individual types of
exchange rate regimes. Thirdly, we will investigate the influences
of selected economic variables on PPP, and finally, we will try to
assess the impact of the on-going financial crisis. Regarding the
first test, we can see from tables nos. (16), (17) and (18) that
there are differences in terms of the groups of countries. While
the results for NMS10 are close to the results for NMS, a more
similar group of countries represented by NMS8 gives significant
support to PPP. The results of the pURTs turn insignificant for the
last subgroup of NMS (NMS5). However, this may have been due
to the limited number of cross sections ( is small), where
the pURTs are less robust.
ER regimes
Another possibility is to distinguish between countries with
respect to their exchange rate regimes. Some countries have
preferred more flexible exchange rate regimes, while others
chose more constant ones. It is rather difficult to classify
individual countries according to this criterion, as some of them
have changed their exchange rate regimes several times (e.g.
Poland). On the other hand, there are countries that have used
66 There have been some studies that used even fewer time observations, see
e.g. Solakoglu (2006) for a test of the PPP theory in CEE countries or Harris and
Sollis (2005) for a test of total factor productivity for OECD countries.
101