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NHANES Dietary Web Tutorial

Estimate Ratios


Dietary researchers are often interested in questions that involve examining two variables in relation to one another.  They might wish to know the ratio of whole milk to low-fat milk, the proportion of calcium intake contributed by milk, or the percentage of energy from fat.  Ratios, including proportions and percentages, are useful devices for addressing such relationships.  


Task 1: Estimate Ratios

Whenever ratios involve the division of one variable by another—both of them, by definition, having varying values across individuals in the population—analysts can use different ways to summarize the ratio, and these different calculations can lead to different answers.  This task describes common methods for calculating ratios in dietary analyses, how they differ, and when to use each.


Task 2: Identifying Important Food Group Sources of Nutrients

There are two different ways to consider food sources of nutrients—as “important” vs. “rich” sources.  Rich sources are those foods with the greatest concentration of a nutrient, whereas important sources are those that contribute the most to a population’s intake.  This task describes methods for identifying important sources. 


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