Meet the recipe tetrahedron, inspired by Ashby plots from the field of materials science. You can print this, cut it out, and fold along the dotted lines to assemble your very own recipe tetrahedron. Boston Globe reporter Carolyn Y. Johnson wrote a great article about this called “The Analyzed Brownie” that comes with a really fun graphic.
The tetrahedron depicts four ingredient dimensions: flour (F), sugar (S), egg (E) and liquid (L). The other primary dimension, missing here, is fat. Each of the four faces of the tetrahedron is a triangle depicting three of these dimensions. As shown in the key, different colors correspond to different kinds of recipes, e.g., brownies are purple and sugar cookies are blue. Each point corresponds to a recipe. A recipe in the center of a triangle has equal ratios by volume of the three ingredients at the corners of the triangle, e.g., a point in the center of the top F-L-S triangle has equal parts flour, liquid, and sugar.
Here are some things to observe:
For more information on using tetrahedra to visualize data, see the Wikipedia page about the simplex.
The data used in this plot was collected by Diana Cai, an undergraduate at Harvard College. This is part of a project with Michael P. Brenner to learn about flour-based baked goods and other foods.