>> There is no scientific reason to use it in statistical investigations in the age of the computer > As someone who uses it daily I am eagerly awaiting his ar

>> There is no scientific reason to use it in statistical investigations in the age of the computer > As someone who uses it daily I am eagerly awaiting his argument. The use of root mean square error|deviation comes from the ease of calculation in the days before computers. Now that we have computers we can just use mean absolute error|deviation. Before computers, we needed calculus to find the "best fit line" -- parameters that create the least distance between predicted and actual values. Calculus plays well with parabolas but not so great with absolute value functions. Now that computers are around, we don't need calculus (as much).