To estimate usual intake distributions of foods and nutrients, researchers are recommended to collect non-consecutive repeated 24-hr dietary recalls. However, resource limitations sometimes restrict data collection to a single day of dietary data per person. The National Cancer Institute (NCI) 1-day method, a new statistical method, uses single-day dietary intake data and an external estimate of within- and between-person variation to estimate population distributions of usual intake of nearly-daily consumed foods and nutrients. The details of this method, and the results of comparisons of the 1-day method with the corresponding NCI method that uses 2 or more days of data, have been published by Luo et al (Accepted for publication by Journal of Nutrition).
The new method is implemented in a SAS macro (called *TRAN1* v.1.0) designed to be compatible with the existing NCI macros, allowing the user to conduct the same kinds of analyses. The new SAS macro *Tran1*, a corresponding user manual, and example code and data are available on the page. The content of each folder is described as follows,
1. Under the “input_data” folder:
sample data (**indiv_ims.sas7bdat**), containing demographic information and dietary recalls from the National Health and Examination Survey 2004-2008. The sample dataset is provided here as a courtesy. For the latest version, users should download the sample data via the National Cancer Institute website at https://epi.grants.cancer.gov/diet/usualintakes/indiv_ims.zip
2. Under the “macro” folder:
- *TRAN1* macro (**tran1_macro_v1.0.sas**).
- *TRAN1* macro user guide (**tran1_user_manual_v1.0.pdf**).
- *DISTRIB* macro (**distrib_macro_v2.1.sas**). The DISTRIB macro is provided here as a courtesy. For the latest version, users should download *DISTRIB* macro at https://epi.grants.cancer.gov/diet/usualintakes/macros_single.html.
3. Under the “code” folder:
Sample code to estimate usual distribution of folate intake among U.S. adult male using *TRAN1* and *DISTRIB* macros (**folate_analysis_oneday.sas**).
4. Under the “output” folder:
Outputs from *TRAN1* macro to be used in *DISTRIB* macro:
- Estimated coefficients of covariates, transformation lambda, and values of within- and between- variance (**_param_unc_dfe.sas7bdat**).
- Estimated linear prediction (**_pred_unc_dfe.sas7bdat**).
Outputs from *DISTRIB* macro:
- Mean and percentiles of usual folate intake among male adults (**descript_dfe_rndw1.sas7bdat**).
- Monte Carlo dataset for pseudo people (**_mcsim_dfe.sas7bdat**).
