The stacked bar chart summarizes the cost of the ingredients for Steak ’n’ Bacon Cheddar Meatballs at Amazon's Whole Foods and at Walmart. The ingredients cost 66% more at Whole Foods, according to the New York Times . The cost of each ingredient, except onions, was higher at Whole Foods. The biggest absolute cost difference was for olive oil, which cost $2.20 at Walmart and $6.99 at Whole Foods. The largest percentage difference was for salt which cost 40 cents at Walmart and $1.49 at Whole Foods, a 273% difference. Onions cost less at Whole Foods by 32%.
The Times made the purchases at a Whole Foods in Brooklyn and a Walmart in New Jersey. The comparison was not meant to be scientific. The results were prepared and compared with eaters preferring the meatballs made with the more expensive Whole Foods ingredients. You can see the ingredient by ingredient differences in the stacked bar chart with data columns added for dollar and percentage difference.
Stacked Bar Chart with Data Columns
How I Created The Stacked Bar Chart
I used a stacked bar chart to focus on the overall difference in ingredient costs. The size of each bar provides the visual evidence of the difference. With nine ingredients, it is difficult to see the cost differences between individual ingredients in the stacked bar. The data columns for dollar and percent difference address this shortcoming. The linking lines between the two bars also provide a visual cue.
The Times presented the data in photos of the Whole Foods and Walmart receipts. I entered the data into the Mekko Graphics data sheet and performed the following formatting steps:
- add the formulas for the data columns
- copy the ingredient names from the series names and create a data column for them
- add the linking lines
- remove the x and y axis
- adjust the y axis maximum so that the Whole Foods bar reached near the top of the chart area
- sort the data so that the highest cost items from Whole Foods are at the bottom of each bar
- annotate the labels for salt and onions
- adjust the color palette so that we have two shades of 5 colors
- add totals for the dollar difference and percent difference data columns
- color in red the largest dollar and percentage difference.