Root mean square deviation

Imagine you have some toy blocks of different sizes and shapes. You want to know how different they are from each other. One way to do this is by measuring the distance between each block's corners and the center of the block.

Now, imagine taking many, many blocks and doing this measurement for each of them. You would end up with a list of numbers showing the distance from the center of each block to its corners.

To simplify this list of numbers and get an idea of how far apart the blocks are on average, you can square each number, add up all the squared numbers, divide that sum by the number of blocks, and then take the square root of the result. This is called the root mean square deviation.

In simpler terms, root mean square deviation means finding the average distance from the center of an object to any point on its surface.