What Full Body Composition Scales Teach About Machine Learning
A story of bias and variance
All digital body composition scales are inaccurate; it’s just that some of them are inaccurate in a better way.
What am I talking about? Let’s start from the beginning of the story. This year, I started to take working out very seriously. I train five times per week and do push-ups with one arm. (And sometimes with one leg.)
I am at my peak.
To quantify my progress, I need more than just a simple weight measurement and BMI. I want to track my muscle-fat ratio.
Thus, I decided to get a body composition scale, one that drives a little bit of electrical current through your body and measures how it travels through different types of tissue.
As usual, there are hundreds of smart body composition scales to buy. After watching dozens of reviews, I have realized that almost all of them are inaccurate. However, not all of them are the same. Given two scales, out of which
one is accurate on average, but the measurements are all over the place,
and the other is always off by a constant amount,
which on…