Visualization and Interpretation of HEI Scores
Visualization of HEI Scores: Radar Plots
When using the HEI, it may be helpful to visualize its multidimensional qualities using a radar plot such as the one shown below.
A radar plot displays information about each component score simultaneously. The outer edge of the “wheel” (or end of the “spoke”) represents a score that is 100% of the maximum score for that component, while the center of the circle represents a score of 0% of the score for any component (see Figure 1).
Looking at the collection of component scores in this way may help those using the HEI to visualize patterns of dietary intake and compare differences in diets that may have similar scores overall (see Figure 4), but different component scores contributing to the total HEI score.
When radar plots are used to visualize an HEI score, it is important to display the components in the same order each time so that comparisons can be made. The suggested order of components is: Total Fruits, Whole Fruits, Total Vegetables, Greens & Beans, Whole Grains, Dairy, Total Protein Foods, Seafood and Plant Proteins, Fatty Acids, Refined Grains, Sodium, Added Sugars, and Saturated Fats.
Figure 1. Blank radar plot with no data plotted. For each component, the plot is showing the percentage of total points received, starting with 0% in the center and 100% at the outer edge.
Figure 2. Radar plot showing a perfect score of 100. All components scored perfect scores (100% of possible points).
Figure 3. Radar plot showing 2010 U.S. food supply data. The total score is 50.9. However, one component received a perfect component score, Total Protein Foods, while Sodium scored near 0 points. Visualizing the HEI scores in a radar plot allows a viewer to see which components are contributing to the total score.
Figure 4. Radar plot showing two similar total HEI scores (50.9 vs. 49.3). Though the scores are similar, there are notable differences in variety of protein foods, with one scoring perfectly in Total Protein Foods but lower in Seafood & Plant Proteins, compared to the other scoring perfectly in Seafood & Plant Proteins but lower in Total Protein Foods. Similarly, large differences in component scores between the two plots in the Greens & Beans and Fatty Acid Ratio categories can be visualized with this radar plot comparison.
Interpretation of HEI Scores: Grading
Information on interpretation of HEI scores utilizing grading can be found in the Krebs-Smith SM and colleagues’ Update of the Healthy Eating Index: HEI-2015. See selected HEI publications.