NHANES Dietary Web Tutorial Introduction
What are the NHANES dietary data?
The National Health and Nutrition Examination Surveys (NHANES) dietary
data provide a snapshot of the food intakes and nutritional status of
the U.S. population.
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The National Health and Nutrition Examination Surveys
(NHANES) is the only national survey that collects extensive health and
nutrition information from face-to-face interviews and medical
examinations. For many decades, the National Center for Health
Statistics (NCHS) and the U.S. Department of Agriculture (USDA) have
collected dietary data -- NCHS always collected dietary data as part of
NHANES, whereas the USDA used its own surveys. USDA’s national food
consumption surveys were initially designed to help people achieve
economical and nutritious diets. Over time, these surveys broadened in
scope and purpose to measure knowledge and attitudes about diet and
health as well as to assess food and nutrient intakes.
In 2002, USDA and NCHS integrated their dietary data collection efforts
and the dietary recall data are now collected in a joint survey effort
called What We Eat in America (WWEIA). These data as well as other
NHANES data about dietary supplement use, diet behaviors, and food
frequency information are a valuable resource that respond to a variety
of public health and research priorities. In 2003-2006, the National
Cancer Institute (NCI) supported the inclusion of a Food Frequency
Questionnaire in the NHANES to aid in the examination of usual food
intakes and their relationship to health outcomes.
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Why was this tutorial created?
The NCI,
NCHS, and USDA developed this web-based tutorial to meet the growing
demands of NHANES dietary data users and to promote broader and
more proficient use of NHANES dietary data.
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Whether novice or experienced, all users face similar
challenges when using NHANES dietary data due to the complexity
of the survey design and data structure. This tutorial was designed so
that all users learn to:
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efficiently locate pertinent information on the NCHS
website, which is constantly updated and evolving;
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quickly retrieve NHANES dietary data files and
supplementary information, a frequent challenge given the complex
structure and large amount of data available;
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correctly prepare an analytic dataset and create
appropriate food and nutrient variables; and
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correctly conduct statistical analyses that achieve the
analyst’s research objectives with appropriate attention paid to the
nuances of the data and its complex sample design, weighting
requirements, and data structure.
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What does the tutorial provide?
This tutorial walks you through the steps of conducting an
analytical project from beginning to end, with examples of many common
analytic procedures. Relevant dietary data information and nuances,
tips, and explanations for SAS or SUDAAN programs; downloadable sample
program code; and analytical guidance are organized and integrated into
different modules and tasks to facilitate this learning process.
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The tutorial is intended to be:
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a step-by-step course on dietary data retrieval and
analysis for new users;
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a
self-learning tool for novice and infrequent
users to supplement their knowledge of the wide range of dietary data
available in NHANES and the analysis techniques required to properly
analyze these complex datasets; and
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a
reference for experienced researchers
highlighting NHANES analytic nuances and sample program code.
To best serve the needs of a wide range of users, this tutorial has
included a large amount of information. The information is organized in
such a way that those who would like to review all information may do
so, while others can efficiently bypass sections that are not of
interest to them. Overall, this tutorial provides a complete on-line
learning tool.
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What's the best way to use the tutorial?
Your own background and learning style will dictate how you can best use
this tutorial.
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If you are a beginning NHANES dietary data user,
you may want to work through the tutorial in a linear fashion, starting
with the modules that orient you to the dietary data, then continuing
with the modules about how to prepare an analytic dataset and how to
conduct various types of analyses.
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If you are an
experienced NHANES dietary data user
and you are searching for specific information or types of assistance,
you can pick and choose topics of interest among the modules or even
among tasks within modules.
You are encouraged to use the tutorial's features and content to suit
your own needs:
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a linear path for users who need step-by-step self-guided
training;
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index pages and easy navigation throughout modules that
allow you to limit your training to information on an “as needed” basis;
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checklists, summary tables, and animated demonstrations
with audio explanation to enhance learning;
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real-life examples to assist you through the various
processes of data preparation and data analysis;
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sample code and data files for you to practice skills and
run analyses using your own software;
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annotated results with interpretation to help you
troubleshoot your own analyses; and
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links to related references and outside resources.
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Who is the audience?
We expect users of this tutorial to come from a range of perspectives
and disciplines and to have different levels of experience with NHANES
dietary data and varied degrees of skill in statistics and software
packages.
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Users will likely fall into one of these groups:
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public health and other government staff involved in
NHANES dietary data analyses;
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researchers who use NHANES dietary data for scientific
studies or educational purposes;
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public health and medical professionals who use NHANES
dietary data for planning, policy making, or public health programs; and
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other users of NHANES dietary data or groups interested in
NHANES.
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Page Last Modified:
November 20, 2008
