pool {mice} | R Documentation |
Pools the results of m repeated complete data analysis
pool(object, method="smallsample")
object |
An object of class 'mira', produced by functions like lm.mids or glm.mids. |
method |
A string describing the method to compute the degrees of freedom. The default value is "smallsample", which specifies the is Barnard-Rubin adjusted degrees of freedom (Barnard& Rubin, 1999) for small samples. Specifying a different string produces the conventional degrees of freedom as in Rubin (1987). |
The function averages the estimates of the complete data model, computes the total variance over the repeated analyses, and computes the relative increase in variance due to nonresponse and the fraction of missing information. The function relies on the availability of
R-Specific: The original use of Varcov has been removed to vcov (VR MASS).
An object of class 'mipo', which stands for 'multiple imputation pooled'.
Stef van Buuren, Karin Oudshoorn, 2000
Barnard, J. and Rubin, D.B. (1999). Small sample degrees of freedom with multiple imputation. Biometrika, 86, 948-955.
Rubin, D.B. (1987). Multiple Imputation for Nonresponse in Surveys. New York: John Wiley and Sons.
Alzola, C.F. and Harrell, F.E. (1999). An introduction to S-Plus and the Hmisc and Design Libraries. http://hesweb1.med.virginia.edu/biostat/s/index.html.
lm.mids
, glm.mids
, vcov
,
print.mira
, summary.mira
data(nhanes) imp <- mice(nhanes) fit <- lm.mids(bmi~hyp+chl,data=imp) pool(fit) # Call: pool(object = fit) # Pooled coefficients: # (Intercept) hyp chl # 21.29782 -1.751721 0.04085703 # # Fraction of information about the coefficients missing due to nonrespons # e: # (Intercept) hyp chl # 0.1592247 0.1738868 0.3117452 # # > summary(pool(fit)) # est se t df Pr(>|t|) # (Intercept) 21.29781702 4.33668150 4.9110863 16.95890 0.0001329371 # hyp -1.75172102 2.30620984 -0.7595671 16.39701 0.4582953905 # chl 0.04085703 0.02532914 1.6130442 11.50642 0.1338044664 # lo 95 hi 95 missing fmi # (Intercept) 12.14652927 30.4491048 NA 0.1592247 # hyp -6.63106456 3.1276225 8 0.1738868 # chl -0.01459414 0.0963082 10 0.3117452