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19 19.5 20 20.5 21 21.5 22 22.5 23 Age
Figure 4. Age Profiles for Death Rates by External Cause
Notes: See notes to Figure 3. The categories are mutally exclusive. The order of precedence is homicide, suicide,
MVA, deaths with a mention of alcohol, and deaths with a mention of drugs. The ICD-9 and ICD-10 Codes are
in Appendix C. external injuries. Figure 3 shows a sharp increase in overall mortality at age 21 of
about 10 deaths per 100,000 person years. Grouping the deaths by cause reveals that
for this age group the majority of deaths are due to external causes and the increase
in deaths at age 21 is attributable largely to deaths due to external causes.
Table 4 presents the regression estimates corresponding to Figure 3. The dependent variable in the regression is the log of the total number of people who died
at an exact age (in years and days) during the 1997–2004 period. We estimate the
model over the 1,460 days between ages 19 and 22, inclusive.18 The coefficient of
interest on the over 21 indicator can, for small changes, be interpreted as the percentage change in deaths at age 21. In the first column of each panel, we present
the estimates from fitting a quadratic polynomial to the age profile of deaths. In
the second column, we add a dummy for the twenty-first birthday and a dummy for
the day immediately after. In the third specification of each panel, we add a cubic
term to the polynomial. In the fourth column, we present the estimate from a local
linear regression with a rule-of-thumb bandwidth for each side of the age-21 cutoff 18 We did not use the death rates as the dependent variable because measurement error in the denominator
is likely to reduce the precision of the estimates. Rates are unnecessary for the regressions because combining
the cohorts smoothes out most of the bumps in the age profile and the polynomial in age absorbs the remaining
variation. Fortin – Econ 560 Lecture 0 o If results critically depend on a particular bandwidth, they are less credible and
choice of bandwidth requires a substa...
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This document was uploaded on 02/26/2014 for the course ECON 560 at The University of British Columbia.
- Fall '13