ELI5: Explain Like I'm 5

tough to measure, control, or predict

Alright kiddo, so sometimes it's really hard for grown-ups to figure out what's going to happen next or how to make something work exactly the way they want it to. This can be because there are a lot of different factors involved and they all interact with each other in really complicated ways. So even if the grown-ups try really hard to understand everything, it might still be tough for them to measure, control, or predict what's going to happen. It's like trying to build a big tower out of blocks, but not being sure how many blocks you need or how to stack them up just right. Sometimes things are just too tricky for us to figure out completely!