|
|
|
|
|
|
Usual Dietary Intakes: SAS Macros for the NCI Method
NCI has developed three macros for estimating usual intakes. One -- MIXTRAN -- fits the
model to obtain parameter estimates and allows for the evaluation of covariate effects.
The second -- DISTRIB -- uses parameter estimates from MIXTRAN and a Monte Carlo method to
estimate distributions of usual intake. These macros can be used jointly to estimate the
distribution of usual intakes of both foods and nutrients. The third -- INDIVINT -- can
be used together with MIXTRAN to predict individual food or nutrient intake for use in a
disease model. The MIXTRAN macro alone is sufficient for testing covariate effects on
either food or nutrient intakes. The DISTRIB and INDIVINT macros are generally used in
conjunction with the MIXTRAN macro.
Documentation for all three macros is provided in the
User's Guide for Analysis of Usual Intakes
(PDF).
To help analysts get started, NCI has developed several sample programs and analytic
datasets. These programs employ the various macros in conjunction with preliminary
analytic datasets containing data from the National Health and Nutrition Examination
Survey (NHANES). The first three examples use a dataset that is based on NHANES 2001-04
data; it includes the addition of balanced repeated replication (BRR) weights, imputed
values for some of the MyPyramid equivalents data, and differences in a few variable
names. The last example uses a dataset based on NHANES 2003-04 data, with a small set of
variables used to illustrate the method.
|
|
