The name is absent

on the model with a drift only. The unit root null hypothesis is rejected at conventional levels
for all series in first differences.

Table 2. DF-GLS unit root tests on the first differences of series

The critical values for 0.95 (0.99) confidence levels with constant are -1.944 (-2.592), with constant and trend
are -3.074 (-3.633). The Akaike Information Criteria was used to determine the lag length.

Because the graphical analysis suggests the possibility of structural breaks, that are not
accounted for by the DF-GLS tests, the Zivot-Andrews unit root test in the presence of
structural breaks is used to double-check the series (table 3).

Table 3. Andrews - Zivot unit root tests

The critical values for 0.95 (0.99) confidence levels in case of a structural break in the intercept only, are -4.80
(-5.34), trend only -4.42 (-4.93), and both -5.08 (-5.57). The Schwarz Bayesian criterion was used to determine
the lag length.

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