of a parabola
occurs through a quadratic
equation. Specifically, a U-shaped parabola in the economic sensible part of
the quadrant requires that α1<0 and
α2>0.
,1999 2012is
rank
2rank
1a 2a2a
1 0a →
small (in the order of 1%) in just 2 to 3
years and
remain small thereafter.
6 Results
6.1 Singles
First we consider the results for singles.11 Figure 2a and 2b present
graphical evidence
for kink →
