ELI5: Explain Like I'm 5

Pseudocount

Hey there, kiddo! So, you know how sometimes when we count things, we start at 1 instead of 0? Like if we're counting our fingers, we start with 1 instead of 0, even though we really have 0 fingers up at that point? Well, that's kind of like what a pseudocount is.

When scientists are trying to figure out how often certain things happen in a group of something - like how often a certain letter appears in a bunch of words, or how often a certain type of protein appears in a bunch of cells - sometimes they want to make sure that they don't accidentally miss anything by starting their count at 0. So instead, they'll add a "pseudocount" of 1 to everything, which just means they're assuming that there's always going to be at least 1 of whatever they're looking for in the group.

It's kind of like if you're playing hide and seek, and you want to make sure you find everyone, so you start out by assuming there's someone hiding in every single spot you look. That way, if you're wrong and there's actually no one there, you didn't accidentally miss anyone.

Hope that helps!