An article about the cost of fresh vs frozen or canned vegetables recently made the rounds on Gizomdo. The data was taken the USDA 2013 Vegetables, cost per cup equivalent data set. The Bite.Gizomoo article did a decent job expounding on the data; however, it may have made an erroneous conclusion. The author represented all the data and stated there was not that much of difference; however, this is a classic visualization mistake. You can see how messy all this data looks in my other article about embedding excel with onedrive. The data is so packed together that it’s impossible to draw any conclusions. However, with a quick pivot and some calculations, it become abundantly clear that, in the case where the same vegetables are available in both fresh and frozen or fresh and canned, the fresh cost per cup is generally quite a bit higher. See the visualization below made in Tableau Public. Any positive value indicates the dollar amount per cup the fresh version of the vegetable is greater than its frozen or canned equivalent, respectively.
I should also add, the USDA made their visualization in Tableau Public too, those guys should know that showing the difference is the way to compare two groups, not comparing multiple bars. Tufte would be ashamed..