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The Diet History Questionnaire (DHQ) is a food frequency questionnaire that was added in 1998 and was administered to both arms of the trial. The questionnaire data has been processed so that the dataset contains nutrient data in grams. Many of the events in the trial occur prior to this questionnaire. To learn more about the Diet History Questionnaire (DHQ) data collected as part of the study, visit the PLCO Diet History (DHQ) documentation page.

For each dataset, a Data Dictionary that describes the data is publicly available. In order to obtain the actual data in SAS or CSV format, you must begin a data-only request. Data will be delivered once the project is approved and data transfer agreements are completed.

User Guides and Other Files

User Guides are intended to serve as a guide to using the data contained in these datasets.

PLCO User Guide
(PDF - 291.4 KB)
For Diet History Questionnaire (DHQ) Data:
Data Dictionary
(PDF - 1.1 MB)
User Guide
(PDF - 368.5 KB)

Data-Collection Forms

The following forms were used to collect data that is now available in the datasets listed above. They are provided in PDF format.

Dietary History Questionnaire
DHQ - Scanned (6.1 MB)