Estimate Ratios

Purpose

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.

• Key Concepts about Estimating Ratios
• How to Estimate a Ratio of Means Using SUDAAN
• How to Estimate a Ratio of Means Using SAS
• How to Estimate a Mean Ratio Using SUDAAN
• How to Estimate a Mean Ratio Using SAS

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. 

• Key Concepts about Identifying Food Group Sources of Nutrients
• How to Identify Important Food Group Sources of Nutrients Using SUDAAN
• How to Identify Important Food Group Sources of Nutrients Using SAS

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