A note on the standard deviation In this article when we say standard deviation it refers to relative standard deviation. Relative standard deviation here is the ratio of the standard deviation compared to the average piece size. Onions and onion pieces are 3D objects with volumes, but we’re analyzing areas of 2-dimensional cross-sections to simplify the math. Optimal techniquesWe looked at all 19,320 combinations of onion layer numbers, vertical/radial cut numbers, radial cut depth (as whole number percentages), and horizontal cut numbers that are possible with this model. Radial cuts are usually more consistent than vertical cuts, but you have to aim below the center of the onion.