Stability Across Cohorts in Divorce Risk Factors - Bishop Ireton High ...

340 Demography, Volume 39-Number 2, May 2002
Table 2. Estimates of Model Fit for Models Involving an Interaction Between Each Predictor
Variable and Year Married
Model χ 2 / df BIC
Model Model χ 2 df Difference BIC Difference
A: Baseline Additive Model 2,929.58 22 –– –2,732.96 ––
B: A + Age at Marriage × Year Married
C: A + Husband’s Age at Marriage × Year
2,933.14 23 3.56/1 –2,727.58 5.38
Married 2,938.39 23 8.81/1 –2,732.83 0.13
D: A + Premarital Birth × Year Married 2,933.14 23 3.56/1 –2,727.58 5.38
E: A + Premarital Conception × Year Married 2,929.80 23 0.22/1 –2,724.24 8.72
F: A + Wife Older × Year Married
G: A + Wife Has More Education × Year
2,930.51 23 0.93/1 –2,724.95 8.01
Married 2,931.93 23 2.35/1 –2,726.37 6.59
H: A + Husband Older × Year Married 2,939.01 23 9.43/1 –2,733.45 –0.49
I: A + Wife’s Education × Year Married 2,932.22 23 2.64/1 –2,726.66 6.30
J: A + Husband’s Education × Year Married 2,929.89 24 0.31/2 –2,715.40 17.56
K: A + Catholic × Year Married 2,936.00 23 6.42/1 –2,731.44 1.52
L: A + Wife’s Parents Divorced × Year Married 2,931.14 23 1.56/1 –2,725.58 7.38
M: A + Black × Year Married 2,953.24 23 23.66/1 –2,747.68 –14.72
N: A + All Interactions With Year Married 2,980.33 35 50.75/13 –2,667.52 65.44
Notes: All models include a control for survey round. N for the calculation of BIC is 7,611. Values in italic type are
statistically significant at p < .05. Values in bold italic type show strong evidence using BIC for rejecting the null hypothesis of a
zero effect.
the husband being older, being Catholic, and being black. However, the BIC statistic indicates
only one interaction with positive evidence that the null hypothesis of no change
across time should be rejected: the effect of being black.
The results for Model N, which simultaneously includes all interactions with historical
time, indicate a significantly better-fitting model using the LR statistic but not the
BIC statistic. Indeed, the substantial increase in the BIC statistic indicates that this model
may be overparameterized (i.e., may contain too many nonsignificant parameters). The
individual coefficients from this model, however, are instructive: they indicate that when
all interactions are considered simultaneously, the only significant interaction, using either
the LR or BIC statistic as the criterion, is that associated with being black (results
not shown). This result provides further support for the notion that the only substantial
interaction with time involves blacks.
Hazard ratios from bivariate Cox regression models, the additive multivariate baseline
model (Model A in Table 2), and the model including the interaction between year of
marriage and being black (Model M in Table 2) are shown in Table 3. The hazard ratios
shown (e β ) represent multiplicative effects on the hazard of marital dissolution at any
marital duration. Hazard ratios greater than 1 indicate a positive effect, and hazard ratios
less than 1 indicate a negative effect. The percentage difference in the risk of divorce at
any marital duration associated with a unit change in a predictor variable can be calculated
by subtracting 1 from the hazard ratio and multiplying by 100.