samlet årgang - Økonomisk Institut - Københavns Universitet

180
Per cent
40
35
30
25
20
15
10
5
0
60 61 62 63 64 65 66
Retirement age
(a) PEW1 before 1992 PEW1 after 1992 (b)
NATIONALØKONOMISK TIDSSKRIFT 2005. NR. 2
Per cent
40
35
30
25
20
15
10
5
0
60 61 62 63 64 65 66
Retirement age
PEW2 before 1992 PEW2 after 1992
Figure 3. Distrubution of the retirement age among 60-66-year-olds before and
after 1992, (a) VERP1, (b) VERP2.
6.2. Trend adjusted difference-in-differences estimates
That Figures 3a and 3b indicate that the changes in 1992 did not work as intended
might result from other influences affecting not only the VERP sample group but also
other individuals. Therefore, trend adjusted difference-in-differences analyses are
conducted in which the comparison group is used to control for these other influences. 21
Information about gender, education, cohabitation status, experience, lagged unemployment
and lagged income is included in these and the subsequent analyses. The
estimated coefficients on these variables are not reported in the tables but are available
on request.
The difference-in-differences estimates that are adjusted for differential trends on
the sample of 60-66-year-olds suggest that the average retirement age did not increase
as intended (see Table 1 below). Certainly, a positive coefficient for the interaction
term equal to the product of the dummies for year, group and adjustment for different
trend is found for VERP1 as well as VERP2. However, despite the inclusion of the
adjustment variable, the effect on the average retirement age is insignificant for both
groups. The retirement age is lower for individuals entitled to VERP as expected.
The results suggest that the change of the VERP policy in 1992 did not increase the
average retirement age significantly as intended. However, the effect of the change
21. This analysis might suffer from the Ashenfelters dip problem pointed out by one of the anonymous referees.
If the behaviour of the two groups differs substantially before the reform, the identified effects might
be catch-up effects rather than effects of the reform. Because of the number of control variables included in
the analysis (see note to Table 1), group differences in behaviour arising due to other reasons have been
adequately controlled for.