This isn't directly related to class, but I thought someone might be
able to give me some idea why this is happening. I've run the same
model with zelig and with lm. I'm getting differences that are
substantially different. The output and calls are below. Theories?
Imputation:
mi3 <- amelia(data=m3sample, m=10, p2s=0, frontend=FALSE,
idvars="WTSTRAT", startvals=0, tolerance=0.0001, outname="m3outdata",
write.out=TRUE)
m3.1 <- read.csv("m3outdata1.csv")
m3.2 <- read.csv("m3outdata2.csv")
m3.3 <- read.csv("m3outdata3.csv")
m3.4 <- read.csv("m3outdata4.csv")
m3.5 <- read.csv("m3outdata5.csv")
m3.6 <- read.csv("m3outdata6.csv")
m3.7 <- read.csv("m3outdata7.csv")
m3.8 <- read.csv("m3outdata8.csv")
m3.9 <- read.csv("m3outdata9.csv")
m3.10 <- read.csv("m3outdata10.csv")
ZELIG:
Model: ls
Number of multiply imputed data sets: 10
Combined results:
Call:
zelig(formula = ACCULT ~ TIME + PCTH2 + CONTACT + SEND + VISIT2 +
LIVED + MEXICAN + MALE + EDU + INCOME + AGE, model = "ls",
data = mi(m3.1, m3.2, m3.3, m3.4, m3.5, m3.6, m3.7, m3.8,
m3.9, m3.10), weights = "WTSTRAT")
Coefficients:
Value Std. Error t-stat p-value
(Intercept) 4.32459 2.38034 1.81679 7.004e-02
TIME 0.25307 0.03718 6.80730 1.874e-10
PCTH2 -5.02070 1.65078 -3.04141 2.533e-03
CONTACT 0.73485 0.14803 4.96431 1.127e-06
SEND -2.00209 0.75850 -2.63953 8.410e-03
VISIT2 0.17439 0.21159 0.82417 4.100e-01
LIVED -0.51087 0.85970 -0.59424 5.526e-01
MEXICAN -1.02115 1.14343 -0.89306 3.730e-01
MALE 0.06435 0.69695 0.09233 9.265e-01
EDU 2.11346 0.35462 5.95983 6.801e-09
INCOME 0.99713 0.25999 3.83522 1.713e-04
AGE -0.19368 0.03041 -6.36831 2.627e-10
For combined results from datasets i to j, use summary(x, subset = i:j).
For separate results, use print(summary(x), subset = i:j).
LM:
Call:
lm(formula = ACCULT ~ TIME + PCTH2 + CONTACT + SEND + VISIT2 +
LIVED + MEXICAN + MALE + EDU + INCOME + AGE, data = mi(m3.1,
m3.2, m3.3, m3.4, m3.5, m3.6, m3.7, m3.8, m3.9, m3.10), weights
= WTSTRAT)
Residuals:
Min 1Q Median 3Q Max
-11.8463 -3.6531 -0.0422 2.9975 15.3804
Coefficients:
Estimate Std. Error t value Pr(>|t|)
(Intercept) 2.8595 2.1757 1.31 0.1899
TIME 0.2472 0.0321 7.69 3.3e-13 ***
PCTH2 -4.4872 1.5051 -2.98 0.0031 **
CONTACT 0.8163 0.1340 6.09 4.1e-09 ***
SEND -2.0498 0.7187 -2.85 0.0047 **
VISIT2 0.1259 0.1999 0.63 0.5294
LIVED -0.3668 0.7874 -0.47 0.6417
MEXICAN -0.9188 0.9988 -0.92 0.3585
MALE 0.1749 0.6460 0.27 0.7868
EDU 2.2613 0.3196 7.08 1.5e-11 ***
INCOME 1.0732 0.2264 4.74 3.6e-06 ***
AGE -0.1902 0.0290 -6.57 2.9e-10 ***
---
Signif. codes: 0 ?***? 0.001 ?**? 0.01 ?*? 0.05 ?.? 0.1 ? ? 1
Residual standard error: 5 on 253 degrees of freedom
Multiple R-Squared: 0.637, Adjusted R-squared: 0.621
F-statistic: 40.3 on 11 and 253 DF, p-value: <2e-16
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