People really want to make this no-needle blood test thing work, don't they? The most convincing-sounding argument I've heard against this whole idea is this:

People really want to make this no-needle blood test thing work, don't they? The most convincing-sounding argument I've heard against this whole idea is this: Imagine you have a big ball pit with red and yellow balls and you want to estimate how many yellow balls are in the pit. If there are 10,000 red balls and 100 yellow ones, and you sample 10 balls, your sample is just going to be too small to confidently conclude anything about the proportion of balls in the pit. Any biotech/medicine folks care to comment on the accuracy of this metaphor?