21
Translating this percentage into the average number of days, the Bill reduced inpatient
care days by 6.7 days for ages 56-70.
23
We can also see that the results are quite robust
to the inclusion of control variables.
The results in columns (4) and (6) for the age spans 56-60 and 61-70 (which include
controls) respectively, indicate that the point-estimates of the reform effects are almost
the same as in age group 56-70 (about 35 percent reduction in comparison to the control
group), but that the estimate is less precise for the outcome restricted to the age span 56-
60. The effect is statistically significant when measuring outcomes at ages 61-70.
Translating this percentage into the average number of days in inpatient care, the reform
reduced inpatient care by 2.0 days and 4.7 days in the age spans 56-60 and 61-70
respectively.
Table 3: Effects of the early retirement offer on number of days inpatient care
Ages 56-70
Ages 56-60
Ages 61-70
(1)
(2)
(3)
(4)
(5)
(6)
Effect
-0.4989**
-0.3472*
-0.6424†
-0.3413 -0.4331** -0.3540*
(0.1729)
(0.1446)
(0.3383)
(0.2574) (0.138) (0.1595)
Controls
No
Yes
No
Yes
No
Yes
Notes: Estimation is performed with the Poisson maximum likelihood estimator. Robust standard errors in (): † p<.1;
* p<.05; ** p<.01. Each cell represents estimates from a separate model. All models include a military dummy and
dummy for cohort 1938-1939. Control variables are county dummies, income and education, and interaction terms
(interactions between military, income, and education, and interactions between cohort, income, and education). The
number of observations is 19,986.
6.2.1 Pooling birth cohorts
Until now, we have focused our analysis on cohorts that are not affected (i.e., born
1931-1932) and cohorts that are most affected by the 1992 Bill (i.e., born 1938-1939).
However, the “middle” cohorts (born 1934-1937) are affected somewhat by the reform
(that is, they were given the early retirement offer later than age 55, but before age 60).
Hence, these “middle” cohorts may also contribute to a pooled estimation of the reform
effect. Pooling birth cohorts should increase the precision of the reform estimate. One
way to pool birth cohorts is to estimate the following model:
( (
|
))
∑
(
)
23
That is, 0.
35
*19.19 = 6.7 days, where 19.19 denotes the weighted averages for number of days in the sample (see
Table 2).
